When I look back to the year 1998, it seemeds that the ports where I worked have made a preparationed for the coming economic take-off in China in the near future.

Since you're looking back at this moment, the sentence is present tense.

Thousands of people worked and lived there, and many cargo ships throngcrowded the harbor.

Frankly speaking, I didn't know what they have taken out of China, but I know that they only brought in a large amount of steel, rice, and cars made in japan ...

China has always been like a bottomless pit that can melt[ absorb | consume ] everything.

No any local authorities had the right to check them, because they did not need to pay taxes.

Army officers used their mobile phones; soldiers hid their pager-beepers in their pockets (while their commanders pretended not to see ithem).

If we got a deal with a captain, they would charge usome money.

So wWe therefore usually tried to hide our vehicle first, when we saw the soldiers leave, then we quickly sentcarried the products into the ship.

I lookLooking back to / at the year 1998, it seemeds that the ports where I worked haved made a preparations for the coming economic take-off in China in the near future.

I assume you’re telling us how it seems to you now when you look back on the past, so I have applied present tense in my corrections.

Instead of “coming… in the near future” you could simply say “imminent”: “China’s imminent economic takeoff.”

Frankly speaking, I didon't know what they have takentook out of China, but they only brought in a large amount of steel, rice, and cars made in jJapan...…

China has always been like a bottomless pit that can melt (absorb?) everything.

I also wonder if you might mean “absorb.” “Melt” would require more explanation for me to understand.

For example, many container trucks from the army transported steel from the port to the factories.

This would read more smoothly if you wrote “many army container trucks” instead of “many container trucks from the army,” since you have to use “from” again later in this sentence.

No any local authorities had the right to check them, and they did not need to pay taxes.

I’m not sure about the relationship between these two clauses. If there is a cause-and-effect relationship, then use “because” as knabenhaft suggested.

Army officers used their mobile phones; soldiers hid their pager-beepers in their pockets (their commanders pretended not to see ithem).

I’m not familiar with the term “pager-beeper”—I’ve only seen them called either “pagers” or “beepers.” I remember they were called “BB口” in Taiwan in the early ’90s. :-)

Some soldiers who guarded the ships cared for us (watched us?) all the time.

“Cared for us” implies that they were concerned for your welfare and took good care of you, like a parent or the staff of a luxury hotel. Since you later say that you tried to hide from them, I think you mean they watched you.

If we got a deal with a captain, they would charge some money.

“Got a deal” seems OK to me. “Made a deal” would sound better, and “scored a deal” would sound cool.

SoTherefore we usually tried to hide our vehicle first, w. When we saw the soldiers leave, thenwe would quickly sentmove the products i/goods onto the ship.

We generally try to avoid beginning a sentence with “so.”

“Sent” does not mean “送”. “Sent” explicitly means that you did NOT carry or move the goods yourself, you asked or ordered someone else (such as a courier) to carry them for you.

We usually say “on board / onto / on” a ship, not “in.”

I look back to the year 1998, i. It seemed that the ports where I worked haved made a preparations for the coming economic take-off in China in the near future.

"coming" and "near future" seem redundant

Thousands of people worked and lived there, and many cargo ships thronged the harbor.

or: the harbor thronged with cargo ships

Frankly speaking, I didn't know what they have takend exported out of China, but only brought in a. All I knew was that they had imported large amounts of steel, rice, and cars made in jJapan...

China has always been like a bottomless pit that can melt everything.

What are you trying to convey here :? (Although this is a new paragraph, how does this connect with what you are talking about?)

The army was also involved in some economic activities during theis period.

For example, many army container trucks from the army transported steel from the port to the factories.

No any local authoritiesy had the right to check them, and they did not need to pay taxes.

Army officers used their mobile phones; soldiers hid their pager-beepers in their pockets (their commander pretended not to see it).

Some soldiers who guarded those ships cared for us all the time.

I don't know if "care" is the right word here; may be "cared to do business with us" or "did business with us"

So weWe would usually triedy to hide our vehicle first, when we saw the soldiers leave, then quickly sentd the products into those ships.

*starting with "so" is fine casually*

I look back to the year 1998, when it seemed that the ports where I worked haved made a preparation for the coming economic take-off in China in the near future.

past perfect tense - actions begun and completed in the past, before something else (the rest of the story that you’re telling) took place

Frankly speaking, I didn't know what they haved taken out of China, but they only brought in a large amount of steel, rice, and cars made in japan...

Be mindful of tense agreement (simple past and past progressive), and make sure the subject is at the forefront when you start a new clause.

China has always been like a bottomless pit that can melt (or: absorb) everything.

I don’t quite know what you mean by “melt” here, but based on the idea of a bottomless pit, maybe absorb would be a more appropriate word for the simile you’re constructing.

No any local authorities had the right to check them, because they did not need to pay taxes.

There’s a causal relationship here, so “because” is appropriate. Remember to use conjunctions to connect your clauses.

Army officers used their mobile phones; soldiers hid their pager-beepers in their pockets (their commander pretended not to see ithem).

pager is the official term, I believe. I assumed “it” referred to the multiple hidden pagers, so I changed it to “them” to account for multiple items.

If we gotmade a deal with a captain, they would charge us some money.

“make a deal” is the expression.

Charge who? You, presumably.

So we usually tried to hide our vehicle first, when once we saw the soldiers leave, then quickly sent the products ionto the ship.

“Once” expresses the urgency better (in my opinion) and sounds a bit more natural.