Objective: To establish a method for determination the content of the organic acids in Malus doumeri. Method :The content of the organic acids in Malus doumeri was determined by HPLC-MS. The Kinetex HILIC100A column(4.60 mm×100 mm

2.6 μm)was used with acetonitrile and acetic ammonia(30 ∶70)as mobile phase. The flow rate was 0.5 μL and the column temperature was at 35 ℃. Result: The recovery of malic acid was 103.07% with RSD 3.85%;the citric acid was 99.51% with RSD 4.12%;and the tartaric acid was 85.03% with RSD 4.39%. Conclusion: The method is sensitive and accurate;it can achieve very good reproducibility and provide the experimental basis for quality control of Malus doumeri.