Abstract: In order to understand main serotypes and their pathogenicity of pathogenic Escherichia coli that caused yellow-white dysentery of piglets in Liangzhou Prefecture, Wuwei City of Gansu Province, 60 anal swabs of piglets were collected from 4 large-scale pig farms in Liangzhou Prefecture. And 20 strains of E. coli were separated by the bacterial isolation and culture methods. And the separated strains were identified as pathogenic E. coli by morphological observation and biochemical test. The results of serotype identification showed that 20 isolated strains were distributed in eight serotypes. And the dominant serotype was O8 （9 strains）, which took 45%of total isolated strains. The results of drug sensitivity test showed that the isolated strains had resistance to common clinical drugs. The research could provide scientific references for the epidemiologic study, diagnosis and immunological control of piglet diarrhea in Liangzhou Prefecture.