Objective To provide basic data for modification of laboratory testing for outbreaks caused by Clostridium perfringens （C. perfringens）， a diarrhea outbreak that may have been caused by polyclonal infection of C. perfringens was analyzed.Methods Anal swab samples of 4 patients with diarrhea were collected. cpa and cpe genes and C. perfringens in original swab samples and enriched samples were detected via real time PCR. Toxin gene test and pulsed field gel electrophoresis （PFGE） were performed for some C. perfringens isolates.Results cpa and cpe genes were positive in samples of 4 patients. One cpe+ isolate was obtained from 18 isolates of C. perfringens from patient 1， and the composition ratio was 5.56% （1/18）. One cpe+ isolate was obtained from 6 isolates of C. perfringens in patient 2， and the composition ratio was 16.7% （1/6）. No cpe+ isolate was obtained from patient 3， and C. perfringens was not isolated from patient 4. Two types （A type and C type） and 5 PFGE patterns were identified in 11 isolates of C. perfringens. Two cpe+ isolates from patient 1 and patient 2 had identical PFGE patterns.Conclusion This outbreak might have been caused by C. perfringens. Considering the delays caused by the implementation of diagnostic standards， comprehensive use of laboratory detection methods can improve the response time of outbreak analysis.