Objective:To identify and determine the impurities in amlodipine beslyate tablets. Methods:The main impurities in amlodipine beslyate tablets were identified with LC－MS,NMR and chromatographic methods. Then the main impurities were determined with C18 column as stationary phase and buffer (pH 3.0)－methanol－acetontrile 50∶35∶15 as mobile phase. Results:The main impurity in amlodipine beslyate tablets was proved to be the dehydration product of amlodipine (Impurity A,IM A). IM A could be completely separated with the established method. It was a linear correlation between the area and the concentration in the range of 0.5~10.0 μg/ml. The Limit of Quantification of the method was 10 ng/ml,recovery was 98.2%(n = 9) and the RSD of the method was 0.2%(n = 6). Conclusion:The main impurity in amlodipine beslyate tablets was IM A. The established method is accurate,simple and is suitable for determination of IM A in amlodipine beslyate tablets.