Abstract: Objective To investigate whether E.coli O157∶H7 exist in Kunming and its distribution, especially in vegetable, food and water. Method In Oct.2001, 155 samples were collected, including feces of chicken, duck and cattle, offal of pig, fish and chicken, raw milk, vegetable, raw and cooked pork, beef and meat stuffing, marine product from 3 raising farms, 2 snack bars and 9 farm products markets. We isolated and identified E.coli O157∶H7 according to regular isolating method, molecular biology test and serology test. Results 19 strains of E.coli O157:H7 were isolated and all of them had pathogenetic gene of Shiga's bacillus toxin VT2.9 strains were isolated from vegeta-bles,3 from chicken offal,2 from raw pig intestine and pot - stewed pork respectively,1 from hydrated dry vegeta-bles,fish offal and marine products respectively.The number of isolated E.coli O157:H7 strains was very big espe-cially in vegetables,the percentage of O157:H7 strains in the total isolated E.coli strains was 43.37%.Conclusion The potential risk of E.coli O157:H7 strains in the total isolated E.coli strains was 43.37%. Conclusion The potential risk of E.coli O157:H7 outbreak exists in Kunming.