The marine "Mussel Watch" concept is using marine bivalves as sentinel organisms for coastal pollution level monitoring and investigation. Based upon this concept, the "China Mussel Watch" system was constructed in 2006. During 2006~2007, the "China Mussel Watch" program was carried out at 75 sampling stations along the Chinese coastal waters and 12 pollutants (including Hg, As, Cd, Cr, Pb, Zn, Cu, Ni, BHC, DDT, PCBs and TPH) was analyzed. This paper described and evaluated the pollution level of the oysters by these pollutants in the South China Sea. According to the data of the "China Mussel Watch" program from 2006 to 2007 and the relative data of the "South China Sea Mussel Watch" program (SCSMW) which initiated at 1989, the temporal and spatial variation characteristics of 12 pollutants along the coastal waters of northern South China Sea during the last 20 years were analyzed and expounded, and the priority pollutants as well as the pollution hotspots which need to be paid more attention to in the future were pointed out and suggested.