Abstract: The antimicrobial effect of ethanol extract from Sorbus sibirica Branch for a series of bacterium and fungi were studied. The extract was also studied for its stability to temperature and ultraviolet radiation . The results indicated that the extract with a certain concentration could effectively inhibit the growth of bacteria and fungi. The MIC was lower and not reduced much when heated at under 121℃ for 30 min,it still shows a strong antiseptic power after a treatment of ultraviolet radiation. The extract has obvious antimicrobial effect on animal tests.

Key words: exrtract of Sorbus sibirica branch(ESSB), minimal inhibitory concentration, minimal bactericidal concentration, stability