The chemical composition of Piper sarmentosum leaves and their antibacterial activity against Staphylococcus aureus were investigated. Seven alkaloid components were isolated and purified from the total alkaloid parts of P. sarmentosum leaves by repeated column chromatography such as silica gel,Sephadex LH-20 and semi-preparative HPLC.According to the spectroscopic data,combined with the physical and chemical properties,their structures were identified as chaplupyrrolidone C (1),chaplupyrrolidone A (2),chaplupyrrolidone B (3),sarmentamide A (4),N-(3-phenylpropanoyl) pyrrole (5),3-(4-hydroxy-3,5-dimethoxyphenyl) propanoylpyrrole (6),3-(3,4,5-trimethoxyphenyl) propanoylpyrrole (7).Accordingly,compound 1 is discovered to be a new amide alkaloid and compound 7 was isolated for the first time from P. sarmentosum.The microbial inhibition activity of all the isolated compounds was tested by the broth microdilution method,and the results showed that compounds 1-4 exhibited different degrees of inhibition against Staphylococcus aureus.