Objective: To determinate the residues of altrenogest in porcine edible tissues （muscle, liver, fat）, a high performance liquid chromatography-tandem mass spectrometry （LC-MS/MS） method was established. Methods: The samples were hydrolyzed with β-glucuronidase/arylsulfase, extracted by acetonitrile （ACN）, purified by PRiME HLB solid phase extraction column. LC separation was performed with Waters UPLC BEH C₁₈ reversed-phase chromatography with a linear gradient elution of acetonitrile （ACN）-0.1% formic acid （FA） as the mobile phase. The samples were detected by electrospray in positive ion mode. Results: The pregnancin in tissues were quantified in the range of 1～50 μg/L with good linearity and high linear correlation coefficient （R²>0.99）. The limit of detection （LOD, S/N=3） and the limit of quantification （LOQ, S/N=10） were as low as 0.5 μg/kg and 1.0 μg/kg separately. Under three different concentrations （1.0, 2.0, 10.0 μg/kg）, the average recoveries were 60.9%～89.8%, the intra-day coefficient of variation was 0.8%～7.1%, and the inter-day coefficient of variation was 2.5%～11.6%. Conclusion: The method is simple and suitable for the qualitative and quantitative analysis of altrenogest residue in porcine edible tissues.