As porcine epidemic diarrhea virus（PEDV）is one of major pathogens leading to diarrhea in newborn piglets，in order to identify the causes of vomiting，diarrhea and high mortality of newborn piglets in a farm in Qujing City of Yunnan Province，tissue lesions including intestines，mesenteric lymph nodes and spleens of dead piglets were collected and extracted for pathogenic nucleic acids after sample treatment，followed by detection of PEDV，transmissible gastroenteritis virus（TGEV），rotavirus（RV），porcine pseudorabies virus（PRV）and classical swine fever virus（CSFV），porcine reproductive and respiratory syndrome virus（PRRSV）and other pathogens that led to the diarrhea by RT-PCR. The results showed that only PEDV nucleic acids were detected positive and all other pathogens were negative. By analysis on the sequence of N gene of PEDV positive samples，it was found that the N gene shared the nucleotide homology of 99.7% with T10-HB2018 strain isolated in Hebei Province，which was highest；97.4%-97.5% with vaccine strain AJ102 and LW/l strain，all of which belonged to gene clusterⅡin the same branch；and 95.7% with classical strain CV777，which was lowest. It was concluded that the diarrhea was mainly caused by PEDV infection，the available vaccines were effective for its prevention and control because no variation had occurred in the prevalent strain. According to the analysis results，emergency immunization with PEDV vaccines was adopted to effectively control the epidemic. Some reference was provided for the prevention and control of diarrhea in pigs in Yunnan Province.