Objective:To compare pharmacokinetics and relative bioavailability of metformin hydrochloride sustained release tablet(the test preparation) with metformin common tablet(the reference preparation). Methods:Twenty male healthy volunteers were enrolled in a randomized two-way crossover design with a single-oral dose study(1 000 mg once per day for each preparation) and a multi-oral dose study(1 000 mg once per day for the test preparation and 500 mg twice per day for the reference preparation). The plasma concentrations of metformin were determined by high performance liquid chromatography(HPLC). A two-compartment model was adopted in metformin plasma concentration-time data analysis. Pharmacokinetics parameters were also calculated and bioequivalent was analyzed. Results:The main pharmacokinetic parameters of the test preparation and the reference preparation were as following:In single-dose group,Cmax was(1.61 ± 0.37) and (2.47 ± 0.74)μg/ml;Tmax(3.1 ± 0.6) and (1.5 ± 0.7)h;T1/2(5.1 ± 1.9) and(2.7 ± 0.3)h;AUC0→t(11.08 ± 2.88) and(12.03 ± 2.63)h·μg/ml and the relative bioavailability of the test preparation was(92.6 ± 14.7)%. In Multi-dose group:Cmax was(1.60 ± 0.25) and (1.57 ± 0.40)μg/ml;Tmax(3.2 ± 0.4) and (1.1 ± 0.5)h;T1/2(5.5 ± 3.1) and (3.0 ± 0.6)h;AUCss(13.24 ± 3.08) and (6.99 ± 1.50)h·μg/ml,and the relative bioavailability of the test preparation was(95.3 ± 17.5)%. Conclusion:The test preparation was bioequivalent to the reference common tablet,and showed the characteristics of sustained release.