The weather in Guangzhou

Well, you have taken this topic as far as you can, I think.  Some of your phrasing is really Chinese... try getting used to thinking in English.  That should help you to sound more natural.  Be careful about using "but" and "although;" they seldom go together, and they change the order of the words in the sentence.  Also be careful with "looking forward to."  

Keep writing, and good luck learning English!  

The weather in Guangzhou
    - this is nitpicky, but for titles of things, everything besides besides prepositions (unless they are the first one) and in/definite articles should be capitalized. correct form: The Weather in Guangzhou

A week to experience the four seasons change in GZ is really [].
    - you missed a word!

Sometimes it's very cold, sometimes it's very warm. But you can see green trees and beautiful flowers everywhere. In [the] summer is becomes hotter and hotter.
    - "in the summer/winter/fall": i checked online, and american english usually requires a "the" whereas british english doesn't. up to you which you prefer, but as an american, it sounds weird to me!
    - "is becomes" isn't a verb form in english. i think you mean to say "it gets hotter and hotter as the summer goes by" or "it gets hotter and hotter in the summer". if you absolutely want to use the verb "becomes", then you must add a subject. "in the summer, the weather becomes hotter and hotter". i think "get" is still the best choice in this case though!

The highest temperature is over 39℃，even hotter than the islands of Southeast Asia. It makes me wonder,but the fact is that.The autumn in GZ is very nice.
    1) i don't understand the function of "it makes me wonder".i would simply delete it.
    2) no period between "is that" and "That autumn" because "that" functions to introduce a clause and that clause is part of the same sentence.

It's my favourite season, neither cold not[nor] hot.
    - don't forget your comma! and i think your not is a typo.

[The] Sky is clear and then air crisp.
    - sky needs an article, and i think "then" is just a typo.

The winter in GZ although it does not snow but [it] still feels cold.
    - the clause "although it does not snow" needs to be moved to the front. "Although it does not snow, the winter in GZ still feels cold".
    - you don't need a "but" because you already express the contrary meaning in "although".

It's wet cold mode. I am look forward to summer and autumn.
    -  in gerund constructions with the verb 'to be' (am + verb[ing]) remember to always add the -ing ending to the verb. ex: "i am speaking to you. i am reading a book". here: i am looking forward to summer and autumn.

* just a small note for formatting: adding a space after the period/comma/any punctuation makes things easier to read!

希望解释不会太混乱, 如果解释需要补充的话就留言吧！

The weather in Guangzhou

Guangzhou lies in the south of China.In spring,the weather is changeable  changes a lot. A week to experience the four seasons change in GZ is really . You can experience all four seasons in a week. Sometimes it's very cold, sometimes it's very warm. But you can see green trees and beautiful flowers everywhere. In summer is it becomes hotter and hotter.The highest temperature is over 39℃，even hotter than the islands of Southeast Asia.It makes me wonder how, but the fact is that the autumn in GZ is very nice.It's my favourite season, neither cold not nor hot. The sky is clear and then air is crisp.The winter in GZ although it does not snow but still feel cold.Although it doesn't snow in GZ, it's still wet and cold. It's wet cold mode. Can't use "mode" for describing weather. 

I am looking forward to summer and autumn.

Great job :) !