Abstract: Objective The present study was conducted tO find out the reason of the food poi-soning incident. Take the effective emergent measures，and put an end to the similar events．Methods The uniformed questionnaire was established to investigate each patient．Randomized case-control study was conducted．The suspicious food was analyzed．The vomit and the suspicious food (I.e．Salt black beans) of patients were collected in order to detect the pathogenic bacteria．Results The attack rate in this food poisoning case was 39.58％(95/240) and the median of the latent pe-riod was 1.67 hours．The results of case-control study showed that there was significant difference between the persons who had eaten salt black beans and those who hadn't (P<0．01)，in which the incidence of the persons who had eaten salt black beans was comparatively high．Bacillus cereuses were found in the vomit of the patients。And the quantity of the Bacillus cereus in the residual salt black beans exceeded the criterion．Conclusion This food poisoning incident was caused by the salt black beans polluted by Bacillus-cereus．It WaS speculated that the batch of salt black beans was polluted by Bacillus cereus during production．