Objective:To observe the clinical efficacy of Yiqi Kaimi Formula in the treatment of slow transit constipation with syndrome of qi and yin deficiency. Methods100 patients of slow transit constipation with syndrome of qi and yin deficiency were randomly divided into the control group and treatment group, 50 cases in each group. The control group was treated with mosapride citrate dispersible tablets, while the treatment group was orally treated with Yiqi Kaimi Formula, with a course of 56 days. The clinical efficacy and recurrence rate were observed, and the changes of main symptoms scores of constipation were compared.  Results: ①A total of 90 patients completed the trial, among 46 cases in the treatment group and 44 cases in the control group. ②The total effective rates were 93.5% in the treatment group and 79.5% in the control group, the clinical efficacy of the treatment group was better than that of the control group (P<0.05). ③Compared with treatment before, the total score and all item scores of main symptoms of constipation were reduced in both groups after treatment (P<0.05). After treatment, except the score of defecation frequency, the total score and all item scores of main symptoms of constipation in the treatment group were lower than those in the control group (P<0.05). ④The recurrence rate in the treatment group was lower than that in the control group (P<0.05).  Conclusion:Yiqi Kaimi Formula shows satisfactory efficacy in the treatment of slow transit constipation with syndrome of qi and yin deficiency, which can remarkably improve the clinical symptoms of patients with low recurrence rate.