Background: Extended-spectrum β-1actamases (ESBLs) is prevalent due to the extensive usage of the extended-spectrum cephalosporins and leads to huge financial loss in the whole world while presenting a challenge to clinical remedy.Objective: To delineate the frequency of occurrence of ESBL in Enterobacteriaceae from Chengdu and confirm the SHV genotype.Materials and methods: A random collection of 153 Escherichia coli isolates (E.coli) and 70 Klebsiella pneumoniae (K.pneumonia) isolates were tested.The amplification products obtained by Polymerase Chain Reaction (PCR) were sequenced.Isolates with novel mutations were transformed to E.coli DH5a.The minimal inhibitory concentration (MIC) was obtained by microdilution method.Results: The relevance ratio of ESBL was 67.7% and the proportion of gene blaSHV was 18.5%.A new genotype of β-lactamase was demonstrated, and submitted to GenBank.12 mutational sitets were found in 28 ESBL-producing isolates including four nonsense mutations.Sensitive-rates of 28 ESBL-producing isolates to imipenem were 100%, resistant-rates to penicillin, amoxicillin, oxacillin were 100%.MIC of DH5α-F8 to penicillin, oxacillin, cefoxitin, cefotaxime, cefepime, cefoperazone/sulbactam, imipenem, netilmicin is 512, 512, 2, 0.03, 0.06, 4, 0.015, and 32 respectively.Discussion and conclusion: ESBL in Chengdu, and SHV-28 is the most prevalent bla.Imipenem is the most effective antibiotic to ESBL, the forth-generation cephalosporins and β-1actamase inhibitor compound are also effective.ESBL is mediated by plasmids and able to spread among different Enterobacteriaceae.New mutations of blaSHV gene exit in Chengdu at least from 2010.