Objective:To observe the clinical efficacy and safety of Modified Gegen Qinlian Decoction combined with basic therapy in the treatment of acute infectious diarrhea with syndrome of intestinal dampness-heat. MethodsA multi-center,randomized,double-blind and placebo-controlled clinical study was performed. 144 patients of acute infectious diarrhea with syndrome of intestinal dampness-heat were randomly divided into the treatment group and control group,72 cases in each group. Both groups were treated with basic therapy of western medicine,and the treatment group was treated with Modified Gegen Qinlian Decoction and the control group was treated with placebo of Chinese medicine additionally. The treatment course in both groups was 3 days. The clinical efficacy was observed,and the changes of TCM syndrome score,antidiarrheal time and leukocytes in fecal microscopic examination were compared.  Results:①During trial,a total of 9 cases were excluded or fell off,and finally 135 cases completed the trial. There were 139 cases in analysis set of modified intent-to-treat(MITT)or safety analysis(SA),among 69 cases in the treatment group and 70 cases in the control group. There were 135 cases in analysis set of per-protocol(PP),among 68 cases in the treatment group and 67 cases in the control group. ②The clinical total effective rate was 94.20% in the treatment group and 85.71% in the control group. The clinical efficacy of the treatment group was significantly better than that of the control group(P<0.05). ③There was statistically significant difference on the average antidiarrheal time between the two groups,and the average antidiarrheal time of the treatment group was obviously less than that of the control group(P<0.05). ④For the comparison between treatment before and after,there was statistically significant difference on the normal rate of leukocytes in fecal microscopic examination in both groups(P<0.05). After treatment,there was no statistically significant difference on the normal rate of leukocytes in fecal microscopic examination between the two groups(P>0.05). ⑤ No adverse reaction was observed in both groups. There was no statistically significant difference on the incidence of adverse reaction between the two groups(P>0.05).  Conclusion:Modified Gegen Qinlian Decoction combined with basic therapy of western medicine can significantly improve the clinical symptoms of patients with acute infectious diarrhea,and effectively shorten the diarrhea time.