Indian passport, i want apply china business visa how to apply where will apply

You may just apply for the China business visa from the China Embassy in Sri Lanka at 120/4, Vidya Mawatha, Colombo 07, Sri Lanka.
The documents you have to submit for the visa application include the followings:
1. your Indian passport that must have more than 6 months validity and over two blank pages left
2. Duly filled China visa application from V2011A & V2011B
3. one passport size photo
4. Invitation letter from an duly authorized Chinese unit or confirmation of invitation
5. copy of your Sri Lanka residence visa
6. two-way air ticket and hotel booking in China

The embassy charges RS.3900 for a single entry China tourist visa if you use the normal service of 4 working days.