Visit visa for China.

Non-Singapore citizens shall provide documents that entitle them to reside for an extended period of time in the SPR,WP,EP,STP,DP. Temporary visitors to Singapore should apply for a Chinese visa in their own country. For the special cases, consular officer has the rights to make the final decision on whether issuing a visa or not.

Considering that you have a two year multi entry Singapore visa, I think you can apply for it in Singapore. However, you have to apply for it via Chinese Visa Application Service Center in Singapore since the embassy in Singapore doesn't accept application from the ordinary passport holders.