A total of 191 Staphylococcus aureus isolates were identified from 893 milk samples taken from raw milk,semi-product milk and finished product milk from 2010 to 2011 in Sichuan.The S.aureus isolates were detected by traditional culture method including gram staining,coagulase reaction,together with Chromagar chromogenic media to improve the accuracy.Totally 21.4% of the samples were contaminated with S.aureus,and the prevalence rates of the raw milk,the semi-product milk and finished product milk were 26.4%,7.1% and 0.0%,respectively.After phenotypic characterization,the presence of classical enterotoxin genes as SEA,SEB,SEC and SED were determined by multiplex PCR in the 121 isolates of S.aureus.The results indicated that 22.3% of the isolates harbored enterotoxin genes and 7.4% of the isolates harbored at least two types of the enterotoxin genes.The prevalence rates of enterotoxin genes in the isolates of raw milk,semi-product milk and finished product milk were 23.9%,0.0% and 0.0%,respectively.The most common was SEA gene( 13.2%),followed by SEB gene( 10.7%),SEC gene( 5.8%) and SED gene( 3.3%).This work had increased our knowledge about the contamination status and toxin genes of the S.aureus during the processing of raw milk and provided evidence for the control of the milk quality and safety.