The purpose of this study was to evaluate the antimicrobial activity of Chrysanthemum buds aqueous extract (CBAE) on Escherichia coli, and discuss its application in meat products. The antimicrobial activity of CBAE against E. coli was evaluated by the determination of diameter of the inhibition zone (DIZ), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The possible action mechanism was revealed by the effect of CBAE on the growth curve, and the changes in intracellular ATP concentration, cell membrane potential, and cell morphology. Finally, the CBAE was used in the preservation of cooked pork. The results showed that the DIZ, MIC, and MBC values of CBAE against E. coli were (12.4±0.32) mm to (13.8±0.41) mm, 10~20 mg/mL, and 20~40 mg/mL, respectively. The CBAE could prolong the retardation period of E. coli, shorten the logarithmic period, reduce the intracellular ATP concentration, cause the depolarization of cell membrane, destroy cell morphology, and lead to cell fluid leakage. In addition, the CBAE could reduce the amount of E. coli during cooked pork storage (P＜0.05), and when the concentration was 1 MIC, the effect of CBAE on the color of cooked pork was not significant (P＞0.05).