OBJECTIVE：To improve the method for the determination of content and related substances of Molsidomine tablet. METHODS： HPLC was adopted to determine the content and related substances， HPLC-MS was adopted for the qualitative degradation impurities in destruction test. The column was Waters Symmetry-C18 with mobile phase of 0.05％ formic acid - methanol （gradient elution） at a flow rate 1.0 ml/min and 0.2 ml/min （respectively for content and related substances determination， mass spectrometry）， the detection wavelength was 210 nm， column temperature was 30 ℃， the injection volume was 20 μl and 5 μl （respectively for content and related substances determination， mass spectrometry）. RESULTS：Each component was well separated under chromatographic conditions； degradation impurities were confirmed； the linear range of molsidomine was 4. 0-28.0 μg/ml （r＝0.999 7）； RSDs of precision， stability and reproducibility tests were lower than 1％； recovery was 97.74％-100.70％ （RSD＝0.49％，n＝9）. CONCLUSIONS： The method is simple， accurate with good specific and high precision， and can improve the quality control of Molsidomine tablet.