Objective To investigate and analyze an outbreak of foodborne gastrointestinal disease induced by different batches from the same food supplier, and to identify the cause of outbreak. Methods The cause of outbreak was analyzed and determined by descriptive epidemiology analysis and statistical analysis of attack rate, along with individual interview for the related hotel workers, self-filling questionnaire, telecommunication and fax interview, evidence collection and hygienic investigation on the site and laboratory tests. The pathogenic factors of the incident were also discussed. Results 46 confirmed cases with the main symptoms of acute gastroenteritis were screened out from related population. The distribution of the onset time was from the evening on July 22 to the next morning and the incidence curve suggested a point source outbreak. Considering all the evidence, an epidemiological correlation was found between the lunch on July 22 and the outbreak. Conclusion A gastrointestinal disease outbreak of food poisoning was occurred among the tourists. The reason of outbreak was that a large batches of food were served for a large number of people and the risk of cross-contamination and proliferation of microorganisms increased during food processing. The suspicious pathogen was vibrio parahaemolyticus.