A method of ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) was developed for the simultaneous determination of 5 alkaloids residues of opium poppy in hot pot soup,including morphine,codeine,thebaine,papaverine and narcotine.The samples were extracted with acetonitrile containing 0.2% fomic acid,and then analyzed by UPLC-MS/MS.The separation was carried out using a Waters ACQUITY UPLCTM BHE C18(1.7 μm,2.1 mm×50 mm) column by gradient elution with ammonia solution(pH 8.0) and acetonitrile as mobile phases at a flow rate of 0.3 mL/min.The five alkaloids were determined in electrospray positive ionization(ESI+) mode under multiple reaction monitoring(MRM),and the analytes were quantified by the matrix-matched standard solution.Under the optimized detection conditions,the calibration curves are linear in the ranges of 0.25-100 μg/L for morphine and codeine,0.05-100 μg/L for thebaine,and 0.05-10 μg/L for papaverine and narcotinum,respectively,with correlation coefficients all more than 0.999.The limits of detection(LODs) and quantitation(LOQs) were in the ranges of 0.9-4.5 μg/kg and 3.0-15.0 μg/kg,respectively.The average recoveries at the spiked levels of 1，5,10 μg/kg(5，25，50 μg/kg for morphine and codeine) ranged from 70.7% to 109.6%,with relative standard deviations(RSDs) not more than 11%.This method is simple and sensitive,and is suitable for the determination and confirmation of five alkaloids residues of opium poppy illegally added in hot pot soup.