I am planning to visit taipei around 20july to 29 July.. Will it be rainy or sunny?Is it a good time ?

Generally, it will be hot and a little wet. According to the past weather records, the rainys days may be more frequent than sunny days. Therefore, simple rainy gear should be necessary to be prepared. Besides, it will be during the typhoon season, so you'd better pay much attention to the report at dur time.

Personally, around Oct. to Nov is the best travel season there.