Abstract: OBJECTIVE To evaluate the quality status of mezlocillin sodium for injection through 204 batches of samples from 20 producers. METHODS The samples and accelerated samples were analyzed by determining water activity, water, and related substances. The volatile substances of butyl rubber closures were studied on patibility between them and mezlocillin sodium for injection. The quality status of samples were evaluated by multi-factors correlation analysis of the determination results. RESULTS The quality and stability of the samples produced by freezing drying were better than those produced by sterilized shipment. The water and temperature were closely related to the quality of mezlocillin sodium for injection and the quality of raw material was the key to the quality of preparation. CONCLUSION The most products quality of mezlocillin sodium for injection meet current standards. The existing standard is in deficiencies’ and need to be improved.