How to get 1 year visa or stay long in China my sister working there..embassy gave me only 14days

Narvin, did you apply for a tourist L type to enter PRC this time? If yes, and you want to stay longer in PRC, you can try to apply for an S1 type next time, or try to change your L type to S1 type after entering PRC. In this case, you can possibly get the S1 type which may allow you to stay for more than 180 days in PRC.
The required documents include your passport, the application form, a passport-style photo, valid registration form of temporary residence, an invitation letter from your sister, and copies of her passport and residence permit in PRC as well as the relationship certificate. After, go to the exit and entry administration of the local PSB to convert the L type to S1 type.