Abstract: In order to explore the effect of oil pollution on the food security of aquatic products in Guangdong coastal waters, a risk grade method of petroleum residue was first proposed, petroleum hydrocarbons(PH) in the oysters (Crassostrea rivularis) collected during 2001~2010 were determined by spectrofluorometry, and the PH level in fish and shrimp was speculated.The results indicated that PH contents in our oyster samples ranged from < 0.2×10^-6 to 36×10^-6(wet weight), and might not make oil taste.The mean content of PH was 9.4×10^-6 which was relatively lower in the oysters from coastal waters in China, but higher than the historical data (6.7×10^-6)during 1989~1992.PH were detectable in 99.3 percents of our samples.16.7 percents of our samples contained more PH than the limit value (15×10^-6, Chinese standard).The annual PH average and the over standard rate in our samples trended to decline during 2001~2006, but slightly rebounded after 2007, especially in the samples from the Pearl River Estuary and from industry-translation areas.Based on the data of this survey and other literature, wededuced that the PH contents in fish and shrimp in Guangdong coastal waters were probably lower than 15×10^-6, seldom higher than 30×10^-6, and also might be lower than above limit or oil taste threshold.