Abstract: The quality difference of pharmaceutical excipients from different sources affects the molding properties of the powder, resulting in changes in the properties of the final product. In this study, the critical quality attributes of hydroxypropyl methylcellulose (HPMC) with different specifications from two manufacturers (manufacturer A and manufacturer B) were characterized including particle size, physical morphology, viscosity and powder physical quality attributes. Aminophylline, diclofenac sodium, and metformin hydrochloride were utilized as model drugs with different solubility to prepare sustained-release tablets, and the effect of HPMC from different sources on drug release of sustained-release tablets in vitro was investigated. The results showed that HPMC with the same viscosity specification from different sources had outstanding differences in the physicochemical properties (including particle size, physical morphology, viscosity, dimension, compressibility and powder flow), which could change the hardness and friability of the sustained-release tablets. The differences in the physicochemical properties of HPMC had different effects on the dissolution of different sustained-release tablets in vitro. It had no significant effect on the release of easily soluble aminophylline and metformin hydrochloride, but had a greater impact on the release of poorly soluble diclofenac sodium. Compared with manufacturer A, the sustained-release effect of matrix tablets prepared by HPMC from manufacturer B was more excellent. The results of this study will provide a theoretical reference on selecting the appropriate excipients for formulation design.