I am a SRILANKAN ,i want to purchase R134A GAS from china so how can i get a chinese visa

You need an invitation letter from the business partner in China for F-visa application.

THEY SAY THAT THE Chinese Government NEED A COMMERCIAL CONTRACT BETWEEN US BUT WE DO NOT HAVE A COMMERCIAL CONTRACT BECAUSE WE BOTH ARE GOING TO START A NEW BUSINESS

Hi, if you were asked to provide it, you'd better follow them if you want to get visa. Or you can try to apply with copy of round-trip air ticket and hotel booking and your updated bank statement.

hi I am sri lankan living in Shanghai married to Chinese well for sri lanka passport u will not get single entry as this is the Chinese policy in order to get a visa as mentioned F for business required bu u must have a letter from a company that you are going to make up business with. good luck.