Abstract: To evaluate bioequivalence and safety of two kinds of metformin hydrochloride sustained-release tablets (test preparation vs reference preparation) under the condition of fed and single administration.A single center, randomized, open, single-dose, two-period, two-sequence, and double-crossover design was used.32 healthy subjects took 0.5 g of test preparation or reference preparation under fed and single-dose administration.4 mL of venous blood was collected from before administration (0 h) to 1, 3, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 15, 24, 36 and 48 h after administration.The concentration of metformin in plasma samples was detected, and then the pharmacokinetic parameters were calculated by WinNonlin 7.0 software.When the 90% confidence intervals of c_max, AUC_0-t and AUC_0-∞ geometric mean ratio of test preparation and reference preparation were within 80.00%-125.00% equivalent intervals respectively, the bioequivalence of the two preparations was proved.One subject fell off due to adverse events.The main pharmacokinetic parameters of test preparation and reference preparation as follows: c_max were (0.68 ± 0.14) and (0.65 ± 0.11) mg/L, AUC_0-t were (7.33 ± 1.65) and (7.00 ± 1.89) h·mg/L, AUC_0-∞ were (7.39 ± 1.67) and (7.06 ± 1.91) h·mg/L, respectively.The 90% confidence intervals of the geometric mean ratio of the two main pharmacokinetic parameters were 101.45%-109.14%, 100.08%-112.32% and 100.24%-112.28%, respectively, which fell within the bioequivalence interval of 80.00%-125.00%.There were no serious adverse events and unexpected adverse events during the trial.The results show that test preparation and reference preparation are bioequivalent under fed and single-dose administration, safe and well tolerated in healthy subjects.