OBJECTIVE： To study in vitro bacteriostatic activity of Psoralea corylifolia extract （containing 60％ bakuchiol） to 9 pathogens which may induce bacillary diarrhea. METHODS： Drug sensitivity filter disk method and tube dilution method were used to determine sensitivity， MIC and MBC of P. corylifolia extract to Escherichia coli， Staphylococcus aureus， Salmonella pullorum， Bacillus expneumoenteritidis suis， Pasteurella multocida， Streptococcus suis， Listeria monocytogenes， Bacillus paratyphosus and Bacillus cereus. RESULTS： In the in vitro bacteriostatic tests， P. corylifolia extract strongly inhibited B. cereus， L. monocytogenes， P. multocida， S. aureus and E. coli， belonging to medium sensitive； MICs were 3.9， 25， 50， 125， 250 μg/ml and MBCs were 7.8， 50， 100， 125， 500 μg/ml， respectively. B. paratyphosus didn’t influenced by P. corylifolia extract； MICs and MBCs were more than 1 000 μg/ml in other becterial species. CONCLUSIONS： P. corylifolia extract containing 60％ bakuchiol shows in vitro bacteriostatic activity to various pathogens， in which the bakuchiol may play a major role.