Abstract: : Object To study on the antibiotic a ctive constituents ofBalaps japanensis yunnanensis Mars.* . Methods 5 compounds were obtained by solvent extraction, and silica gel column chromatography. Results They were identified as 2-methyl-1, 4-benzenediol (Ⅰ); hydroquinone (Ⅱ); dotriacontanoic acid (lacceroic acid) (Ⅲ); palmitic acid (Ⅳ) and triacontanol (Ⅴ), by spectroscop ic analysis (IR, FABMS, EIMS, 1HNMR, 13CNMR and DEPT). Phar macological screening showed that compounds Ⅰ and Ⅱ showed antibiotic activiti es. Conclusion The above 5 compounds were isolated from B. japanensis yunanensis for the first time.