My hometown

I (have) lived in Chengdu since 1999. The city (sky is) always cloudy just like London. The (days are) short because (the) city is located in the center of (a) basin. The scenery is very beautiful (in) the countryside around the city. The city is at 30 degrees on the northern latitude and where (it is the) panda's hometown.

Welcome to my hometown.

My hometown

I've lived in Chengdu since 1999. The sky is always cloudy, just like London. The sunshine time is short because this city is located in the center of a basin but the scenery is very beautiful in the countryside around the city. （the city also at the mystery of the 30 degree north latitude). and it is the hometown of the panda.

Welcome to my hometown.

When you said “basin”, I think you meant to say “valley”.

I’m sorry but I didn’t understand “the city also at the mystery of the 30 degree north latitude)”

My hometown
I have lived in Chengdu since 1999.The sky is always cloudy, just like London .The days are short because this city is located in the center of the basi. The countryside around the city has a beautiful scenery. The city is at 30 degrees on the northern latitude. *Pandas originate from Chengdu.
Welcome to my hometown.

* Not sure what you were trying to say here. I assume you meant that pandas originate form Chengdu.