I would like to go there when I have a relatively long holiday, such as the annual leave or the Labor Day or National Day holidays, it won’t be winter because the climate is too bad.. I want to pick a day not during the winter because the weather will not be good for mountain climbing then.

I want to go with my teammates, since we have been to many mountains, t excursions together already. They are all very professional and reliable.

Run-on.

I have been to a place called Yamokogen, in the Ganzi Prefecture, of the Sichuan province,. "Cuo" means lake in Tibetan language, It is a lake on a plateau with about 5050 meters attitude,; we spent two days to hike in the mountains and climbed up 700 meters without meeting any people.

Run on.

We carried more than ten kilograms of items including tents, sleeping bags and food, walkand running out of breath. while walking.

On the top of the mountain, I saw a deep blue lake at the buotton,m and on the other side were three snow-capped mountains standing in front of me. They were on the other side, glowing in the sun.

Run-on and spelling.
Very vivid description, though! I like it, it's rather scenic.

Those snow on the tops reflected sunlightey reflected sunlight on the mountaintop, shining all the way.

This is a really gorgeous sentence. I can really feel the magic of the moment.

It was literally breathe taking, not only because of the extraordinarily beautiful view but also stifled because of the extremely thin air.

Good job on playing on the two meanings of breath taking in the metaphorical and literal sense.

I want to go back to the Tibetan Plateau to upgrade my record and climb a real snow-covered trail., where the landscape and challenges always attract me.

A stray period got in the middle of the sentence in between trail and ,

cClimbing a sSnow-cCapped mMountain

Proper title

I would like to go there when I have a relatively long holiday, such as the annual leave or the, Labor Day or National Day holidays, it won’and where there would not be winter because the climate is too bad.

When listing more than three things separate with commas. Also made it make more sense with the additional information about winter.

I want to go with my teammates, as we have been to many mountains, and they awere all very professional and reliable.

adding conjunctions to sentences

I have been to a place called Yamokogen, in Ganzi Prefecture, Sichuan province,. "Cuo" means lake in Tibetan language, It. Yamokogen is a lake on a plateau with about 5050 meters attitude, wan altitude of 5050 meters. We spent two days to hikehiking in the mountains and climbed up to 700 meters without meeting any people.

I separated the sentences, make the "it" more specific in the third sentence. Also fixed how you said the altitude was 5050 meters.

We breathlessly carried more than ten kilograms of items including tents, sleeping bags and food, walking out of breath.

The last part doesn't fit because it looks like its acting in the list which it isn't.

On the top of the mountain, I saw a deep blue lake at the buottonm, and on the other side there were three snow-capped mountains standing in front of me, glowing in the sun.

Button --> bottom.

Those snow on the tops reflected sunlight, shining all the way down.

more naturally written

It was literally breathe taking, not only because of the extraordinarily beautiful view but also literally, as we were stifled because of the extremely thin air.

Breathe taking --> breathtaking. Extraordinarily is chosen because it is modifying beautiful.

The sSunlight, temperature, and oxygen awere gifts of thefrom God, but we have never noticed about it in our daily life.

Small changes

I want to go back to the Tibetan Plateau to upgrade my record and climb a real snow-covered trail., wher because the landscape and the challenges always attract me.

combined the clauses