To study the effect of Dahuang Chengqi Decoction on escherichia coli in vitro in order to explore clinical application value of Dahuang Chengqi Decoction. Methods:Coat escherichia coli in medium surface culture and add Dahuang Chengqi Decoction. Take both spore and chemoprotective as negative control, record bacteriostatic circle diameter, compare two groups of drug application on escherichia coli in vitro antibacterial effect. Results: Dahuang Chengqi decoction has a certain effect on escherichia coli, bacteriostatic circle diameter went up to 13.9mm which is considered moderately sensitive; Cephalosporin #6 has a strong effect on the antibacterial effect of escherichia coli, bacteriostatic circle diameter went up to 19.1mm, which is highly sensitive. Conclusion: Dahuang Chengqi decoction has good antibacterial effect on escherichia coli in vitro. Further clinical studies can be carried out to apply the decoction to the clinical treatment of mild escherichia coli infections.