Abstract: To compare chemical composition, total flavonoid concentration and antibacterial effects in fresh and dried portulacac herba. TLC was used to compare chemical composition in fresh and dried portulacac herba, and the total flavonoids concentration of the two kinds of portulacac herba was tested using UV spectrophotometry, and the antibacterial effect of the two kinds of Portulacac Herba was compared through Antibacterial experiments. TLC chromatograph shows that there are different kinds spots in the two kinds of portulacac herba. Spectrophotometric analysis indicates that the total flavonoid concentration of fresh and dried portulacac herba is 0.075mg·mL^-1 and 0.041mg·mL^-1, respectively. Antibacterial effect of fresh portulacac herba is better than that of dried portulacac herba. Conclusion: The results of this study illustrate preliminarily that properties of fresh and dried portulacac herba, such as chemical composition, mass concentration and antibacterial effects, are significantly different. The results of this study provide the experimental basis for the clinical use of fresh and dried portulacac herba.