To trace the serological source of two food poisoning cases caused by Vibrio parahaemolyticus(VP) and analyze the relationship between serotypes in the suspect food and patient samples.Methods Based on the GB/T 4789.7-2008method, the detected VP was serotyped, and hemolysin tests were performed. The directly heat-resistant hemolysin gene(tdh), tdh-related hemolysin gene(trh) and toxins regulated genes(toxR) were amplified by PCR. Results9VP serotypes in two food poisoning cases were identified by expanding the identification of suspicious colonies in the sample. There were 13strains of O3∶K6,6strains of O2∶K28,2strains of O1∶K56. The results of tdh gene detection were positive in 17strains from 27isolated VP strains which were consistent with the hemolysin tests.Conclusion Expanding the identification of suspicious colonies contributed to the traceability of food poisoning caused by VP. Although O3∶K6was the major pathogen causing food poisoning, VP serotypes from different samples show diversity. The tdh gene detection is equivalent to the hemolysis test in detecting the VP pathogenicity.