Abstract: Objective:The optimal extraction process of total alkaloids from Metaplexis japonica seeds and its antibacterial activity were studied.Method:Total alkaloid yield as an indicator,based on the single factor experiments,orthogonal experiment to optimize the extraction process of total alkaloids from Metaplexis japonica seeds. Bacteriostatic effects on Staphylococcus aureus,Escherichia coli and Bacillus subtilis by Oxford cup method and two fold dilution method were evaluated. Result:The optimum extraction conditions were:Hydrochloric acid aqueous solution pH2,the ratio of material to liquid 1:20 g/mL,the extraction temperature 70 ℃ and extraction time 2.0 h. Under the conditions,the total alkaloid extraction rate of Metaplexis japonica seeds 2.91%. Total alkaloids from Metaplexis japonica seeds had bacteriostatic activities against Staphylococcus aureus and Bacillus subtilis. The minimum inhibitory concentration was 0.2 and 0.4 mg/mL,respectively. It had no bacteriostatic activity against Escherichia coli. Conclusion:The optimization process had good feasibility and the total alkaloids of the Metaplexis japonica seeds had certain bacteriostatic effects.