The village where I was born and raised is located in the mid - eastern part of China.

If you say east(ern) without a qualifier like north east or south east, then it's assumed to be the centre of the east.

Eastern is a little more natural than east for discussing a region of a country

The only difference is only their size.

Sounds a bit more natural to move the only, though your original position was also grammatically correct

WithIn this water, people fed ducks and fish.

"with this water" makes it sound like you fed the fish the water.

On both sides of the body of water body, there were many reeds growing.

Along the moat, there were many different trees growing, among which there was broussonetia papyriferamulberries.

The latin scientific name is not really used in common conversation for types of tree. You could say "paper mulberry" if you want to be super specific about which type of tree, but I think people would probably just use the more general term.

In summer, it was common to see the reeds shaking as a result of fish biting them underwater, and fish just beneath the water surface opening their big mouths to fight for the red, round fruits of the broussonetia papyriferamulberry tree.

My village has a moat, which mainly serves to protect it from thieves.

My village has a moat, which is used it protect it from thieves.

In the moat, there used to be a lot of water.

On both sides of the water body, there were many reeds growing.

On both sides*

In summer, it was common to see the reeds shaking as a result of fish biting them underwater, and fish just beneath the water surface opening their big mouths to fight for the red, round fruits of the broussonetia papyrifera tree.

In the summer, it was common to see the reeds shaking as a result of fishing biting them underwater. In addition, fish were just beneath the water surface and they always open their big mouths to fight for the red, round fruits of the broussonetia papyrifera tree.

In winter, the water in the moat froze.the winter*

WithIn this water, people fed ducks and fish.

This sentence could be understood as people from your village are giving fish and ducks water to eat. If you use the word “in” instead of “with” that would change the meaning of the sentence to people from your village are putting food in the water so ducks and fish can eat it.

On both sides of theis body of water body, there were many reeds growing.

Using the term body of water will make the sentence sound more natural.

The village where I was born and raised is located in the mid - -east part of China.

With hyphenated words, you don't need spaces around the hyphen.

With thihen there was water, people fedwould feed the ducks and fish.

Your original sentence makes it sound like people were feeding water to the ducks and fish. I rewrote the sentence to make it sound better to me.

In winter, the water in the moat frowould freeze.

I think it sounds better to say "would freeze" instead of "froze" here, since it's something that happened habitually in the past, rather than a single event.