Objective To identify the pathogen in the food and the source of infection that might be responsible for a food poisoning outbreak for the banquet in the countryside, and provide evidence for control measures. Methods Case survey, descriptive epidemiological analysis and case study were conducted. A case-control study on 108 people was conducted to identify the foods that might be responsible for this event. Clinical sample from the cases and food processing staff, food and water samples were collected for laboratory detection. Results The attack rate of this event was 21.6% (138/640), and the main clinical symptoms were diarrhea, abdominal pain and fever. 94.4%(51/54) of the cases and 66.7%(36/54) of the controls ate the dishes of cold dish-mixed, the risk of eaten cold dish-mixed was increased (OR=8.50,5%CI: 2.32-31.02). Data from the crossover analysis result showed that the risk of outbreak increased if more than two ingredient of the cold dish-mixed were eaten (OR=9.25,5%CI:2.46-34.82). Four cases were detected Salmonella in serum type B group from their anus swabs and the same bacteria type was also detected in the guan du ingredient of the cold dish-mixed. The result of pulsed field gel electrophoresis for the 5 strains of Salmonella were highly homologous which indicated that the strains was from the same source of exposure. Conclusion Salmonella in serum type B group was responsible for this outbreak which contaminated the cold dish-mixed during food processing. The risk of foodborne disease outbreak was high in rural area, and the supervision in this situation should be strengthened.