Abstract: OBJECTIVE To establish the detection method for the determination of counterfeit Frritillaira in Chuanbei Qingfei syrup by UPLC-MS/MS. METHODS The samples were diluted, and separated on a BEH C₁₈(2.1 mm×100 mm, 1.7 μm) column.The mobile phase were acetonitrile and 5 mmol×L^‒1 ammonium acetate(containing 0.1% formic acid) with gradient elution. The 5 alkaloids in genuine Fritillaria chuanensis and its confounded varieties of homemade control syrup and 50 batches of Chuanbei Qingfei syrup were detected by electrospray ion source(ESI⁺) and multiple reaction detection(MRM) mode. The 5 alkaloids were sipeimine-3β-D-glucoside, peimine, peiminine, sipeimine, peimsine. RESULTS The detection of sifritiline and sifritiline glycosides could distinguish the feeding conditions of genuine Fritillaria chuanensis, Hubei Fritillaria chuanensis, Zhejiang Fritillaria chuanensis and Fritillaria chuanensis in the Chuanbei Qingfei syrup. In the 50 batches of Chuanbei Qingfei syrup, sifritiline and sifritiline glycosides were not detected in 5 batches, which was suspected of using counterfeit Fritillaria chuanensis. CONCLUSION This method has the advantages of high selectivity, high sensitivity and simple sample extraction, and can be used to screen counterfeit Frritillaira in Chuanbei Qingfei syrup.