Abstract: The HPLC-MS/MS was used to determine 9 β2-agonists residuals in pork. The sample was hydrolyzed by β-glucuronidase/aryl sulfatase. The protein was precipitated with perchloric acid and removed by centrifugation. The supernatant was purified by PCX solid phase extraction column with a mixture of ammonia and methanol (5+95) as eluent. The eluate was dried under N2 stream,then the residue was dissolved with 1 mL acetonitrile. The CAPCELL PAK CR column was used as stationary phase and the mixture (contain 0.1% φ) of 10 mmol·L-1 ammonium acetate and acetonitrile (55+45) was used as mobile phase for elution. ESI+ and SRM were adopted in MS/MS. The linear relationship between the peak area and the mass concentration of the 9 β2-agonists was in the range of 4.00-100 μg·L-1,with detection limits (3S/N) in the range of 0.09-0.50 μg·L-1. Recovery rates measured by standard addition method were in the range of 83.2%-102% with RSD′s (n=6) in the range of 5.0%-12%.