Abstract: The purpose was to establish a method for determination of sildenafil in Maca products by UPLC-MS /MS.The samples were separated on Agilent SB-C18 column( 1.8 μm,2.1 mm × 50 mm) and eluted using mobile phase of methanol( 10 mmol/L ammonium acetate) : water( 10 mmol/L ammonium acetate)( 90 ∶ 10,v/v) at a flow rate of 0.3 m L/min,the injection volume was 5 μL.MS condition was positive ion mode,collecting multiple reaction monitoring( MRM) mode.Precursors to product ion transitions of m/z 475.3 > 58.1 was to quantify sildenafil,and m/z475.3 > 282.9 was used as qualifying ion for sildenafil. The collision energy was 50 and 60 e V,respectively. The method was linear in the concerntration range of 0.2 ~ 20 μg/L,and the correlation coefficient was 0.9994. The method was accurate,reliable and highly sensitive,and hence it can be applied in the determination of sildenafil in Maca products.