To investigate a food poisoning event in a company by using field epidemiological and hygienic survey methods to analyze the risk factor and propose the measures for prevention and control. Methods According to established case definition, active case searching and interviewing was implemented. Descriptive epidemiology was used to address epidemiologic characteristics, and the retrospective cohort study and dose-response relation study was used to analyze the risk factors. Field hygienic survey was conducted to analyze the influence factors of the incident. Results 40 cases was identified from the company during 19 to 20 Jan,2015, with the attack rate as 19.4% (40/206). The major clinic manifestations of cases were nausea (100%, 40/40), vomiting (82.5%, 33/40), dizziness (82.5%, 33/40), abdominal pain (65.0%, 26/40) and headache (30.0%, 12/40). The epidemic curve indicated the event was related to the exposure of the source of origin. According to the results of retrospective cohort study, eating lentils of “pork with lentils” exposed the lunch on 19 January was a risk factor (RR=8.8,5%CI:1.3-60.8). The result of dose-response relation indicated that more kidney the employee eating, more risk (χ²Trends=7.8, P<0.05). The result of field hygienic survey indicated that the risk factor of the incident was processing time insufficient, which leaded to the lentils was not cooked thoroughly.Conclusion The event of food poisoning was caused by eating undercooked lentils. The food safety awareness of food handlers should be enhanced and the proper cooking methods should be mastered.