An analytical method for the simultaneous determination of gefitinib and its related substances in raw material drugs was developed by using reversed-phase high performance liquid chromatography(RP-HPLC).The analysis was carried out on a Phenomenex Gemini C18 column(250 mm×4.6 mm，5 μm) with acetonitrile-0.15%ammonium acetate(pH 8.5) as mobile phase at a flow rate of 1.0 mL/min,detection wavelength of 255 nm and column temperature of 40 ℃ in a gradient elution mode.Under the optimized conditions,gefitinib and its related substances had good linearities in the range of 0.012 0-4.202 μg/mL (r>0.999 0).Their detection limits were between 0.001 7 and 0.094 1 μg/mL.The average recoveries ranged from 99.7%to 100.9%with relative standard deviations (RSDs) of 0.06%-0.70%.The method was applied in the determination of gefitinib and its related substances in raw material drugs with satistactory results,and the method was sensitive,accurate,and was reliable for the quality control of gefitinib in drugs.