An HPLC-APCI(+)-MS-MS method was developed for the determination of vitamin D2(VD2) and vitamin D3(VD3) in dairy products.The sample was saponified,and then extracted with petroleum ether.Next,the extract was dried with anhydrous sodium sulfate and concentrated below 10 mL via rotary evaporation under the protection of nitrogen.Then it was dried with nitrogen and dissolved with 10 mL methanol.The extract was analyzed by HPLC-APCI(+)-MS-MS using an ACQUITY UPLC BEH C18 column(1.7 μm,2.1 mm×100 mm) as chromatographic column with a mobile phase of methanol and water under gradient elution.The responses of VD2 and VD3 showed good linearities in the range of 0.01-0.2 mg/L,with correlation coefficients more than 0.998. The average recoveries were in the range of 83.0%- 99.4%,with RSDs of 2.0%- 8.3%.