Abstract：Objective To establish an HPLC mothod and determine the excipients and preservatives of sisomicin sulfate injection. Methods Using Thermo Syncronis aQ (250mm×4.6mm, 5μm) chromatographic column with acetonitrile-water (using phosphoric acid to adjust pH to 2.2) as the mobile phase was used. The flow rate Objective To improve the analysis method of the related substances of sirolimus capsules, and evaluate the quality reasonably. Methods According to the biosynthetic pathway and the structure of sirolimus, we predicted its processed impurities and degradation impurities. The controlling methods were established through a series of chromatographic optimization. Results The new methods can make up the defections of the detection and the controlling of degradation impurities such as the open-ring and oxidation products, which were generated during pharmaceutical processes or/and storage. The new methods were beneficial for monitoring the quality of the products, and improving the safety of the clinical treatment. Conclusion The new methods are specific, durable and reproducible, and it can evaluate the quality of sirolimus capsules more effectively.