To establish a reliable pretreatment method for β-agonists determination in pork and pork liver with high performance liquid chromatography-tandem mass spectrometry (HPLC/MS-MS) assay.Methods Animal tissue was treated with β-glucuronidase/aryl sulfatase enzyme, purified by solid phase extraction (SPE), and concentrated after elution for HPLC-MS/MS analysis. Experiment conditions on solid phase extraction were optimized. Results Two β-agonists showed good linear relationship within the range of 0.5-10.0 μg/L, and the correlation coefficient was above 0.999. The samples were purified by solid phase extraction column, and the recoveries of ractopamine were 81.4%-121.0% with MCX, 97.0%-113.4% with SCX. The relative standard deviations for different matrix were 5.9%-16.2% for salbutamol and 6.4%-20.2% for ractopamine. The detection limits of salbutamol and ractopamine were 0.13 and 0.14 μg/kg respectively. Conclusion SPE methods were optimized for HPLC-MS/MS detection. The precision and recovery was suitable for the detection of animal origin β-agonist residues.