OBJECTIVE：To explore the similarity of dissolution curves in vitro between Gliclazide sustined-release tablet and original preparations from different domestic manufacturers， and evaluate the internal quality. METHODS：Paddle method was used at rate of 50 r/min， in vitro release test was conducted with release media of pH 6.0 Disodium hydrogen phosphate-citrate buffer solution and pH 6.8 Phosphate buffer solution to compared the similarity of dissolution curves in vitro between Gliclazide sustined-release tablet and original preparations by similarity factor f2 and method of AV value. RESULTS：Similarity factor f2 and method of AV value showed the dissolution curves of test preparations in manufacturer A， C and D and reference preparations were similar in 3 media， while only the dissolution curves of test preparations in manufacturer B and standard preparations were similar in pH 6.8 Phosphate buffer solution. CONCLUSIONS：As well as factor f2， method of AV value can also be used to evaluate the similarity of oral solid preparations in vitro dissolution curve profiles. The results show that there are differences between the Gliclazide sustined-release tablet and original preparations from different domestic manufacturers， and there is significant difference in quality.