A method is described for the identification of degradation impurities in Cefodizime solution by ultra performance liquid chromatography and tandem mass spectrometry(UPLC-MS). UPLC-MS method was used to determine the degradation impurities of cefodizime solution at high temperature, acid-base and oxidation conditions. The method identified impurities as anti-form, Δ3-cephem form and degradation impurity based on analysis retention-times, full scan MS and MS2 spectra among extracts , and their content could be increased by heat, acid-base and oxidation. Cefodizime is unstable when exposed to head, acid, alkali and oxygen. Thus, it should be stored in cold, dark and relative humidity below 60%. In addition, the solution should be freshly used.