Escherichia coli， one of the most important foodborne pathogens， was able to form biofilms to increase the environmental resistance and cause foodborne diseases. The purpose of this study was to investigate the inhibitory effect and it mechanism of the bacteriocin plantaricin YKX on the biofilm of E. coli ATCC25922. The results of crystal violet staining suggested that the treatment with 3/4 MIC plantaricin YKX made inhibition rate of E.coli ATCC25922 biofilm to reach more than 50%. The plate count experiment also indicated that the subconcentration of plantaricin YKX could reduce the number of viable bacteria in the biofilm. Scanning electron microscopy(SEM) indicated that the E.coli ATCC25922 biofilms treated with plantaricin YKX were sparsely distributed and their structures were destroyed. The biofilm of E. coli ATCC25922 treated with plantaricin YKX was observed by laser confocal microscopy. The number of viable bacteria was significantly less than that of the one without plantaricin YKX. When co-cultured with 1/2MIC plantaricin YKX， the extracellular polysaccharide secretion of E. coli ATCC25922 decreased. This study provides a new method for the control of Escherichia coli.