The porin forms main pathway by which bacteria communicate with environment and antibiotics penetrate into bacteria. The decrease in synthesis or absence of porin may hinder antibiotics from penetrating into bacteria, and may result in antibiotics resistance of bacteria. The research of role of porin in antibiotics resistance of bacteria has received increasingly more attention. In this paper, the structure and transcriptional regulation of the porin of Escherichia coli and Klebsiella pneumoniae and its association with antibiotic resistance are reviewed.