To investigate the presence and contamination levels of Norovirus ( NoV) in commercial oysters in Guangdong Province from 2011 to 2012, provide suggestions on reducing NoV contamination in oysters, and to prevent and control gastroenteritis outbreaks caused by NoV.Methods Between March 2011 and October 2012, oyster samples collected from several coastal cities in Guangdong Province were examined for NoV by real-time RT-PCR. The contamination levels and genotype of different cities,seasons and sampling sites were compared.Results The overall detection rate of NoV was 14.9%(41/275). In addition, the detection rate was 4.4%, 15.7%, 18.2% and 36.7% in spring, summer, autumn, and winter, respectively. Among 275 samples, 4.0% belonged to GI, 6.2% GII, and 4.7% both GI and GII.Conclusion No significant differences were found in NoV contamination levels and genotye among markets, restaurants, and various cities from 2011 to 2012. However, there were obvious differences in different seasons, especially in winter whick had the highest NoV contamination level in oyster.