Why did China decide to create their own social media platforms and ban the other ones?

To have a complete control on the informations flux, instead of letting private companies do !

chiness the dont trust social media from usa specially 

China wants its domestic firms to develop and not get shouted out by multi-billion dollar Giants.

China likes to control the message and censor the media, some foreign companies play ball (Yahoo! and Microsoft) while others refuse (Google, Twitter, Wikipedia[1]). Google used to comply with Chinese censorship, then suddenly it withdrew and redirected all its search traffic to their Hong Kong site instead of the .cn site.

China popularizes and develops its platforms by banning analogs and wants to control the information flow in social networks

The Chinese Government Wants To Monitor The Information Flow 

Because, The Government Wants To Monitor The Information Flow and Censor Those Info Which Does Not Align With Their Status Quo.

in order to have a control about them information

when you own something you know everything about thus become easy to control it and watch over it

First, China is still communism and does not want to introduce modern democracy. Second, because competition with Western companies will seem difficult, especially since social networks have become the first platform for marketing, especially since the most popular social networks in the world is an American origin.