Objective:To observe the clinical efficacy of Sanhuang Jiedu Decoction combined with metronidazole in the treatment of acute pericoronitis,and the influence on the periodontal microflora,erythrocyte sedimentation rate(ESR)and C-reactive protein(CRP). Methods114 patients with acute pericoronitis were randomly divided into the control group and treatment group,57 cases in each group. The control group was treated with metronidazole powder after rinsing the wisdom tooth crown and blind bag,and the treatment group was treated with sponge dipped Sanhuang Jiedu Decoction based on the treatment for the control group,with a course of 3 days. The clinical efficacy was observed,the changes on traditional Chinese medicine(TCM)syndrome score,periodontal microflora,ESR and CRP were compared.  Results:①Compared with treatment before,the TCM syndrome score was decreased in both groups after treatment (P<0.05). After treatment,the TCM syndrome score in the treatment group was significantly lower than that in the control group (P<0.05). ②The total effective rates were 98.25% in the treatment group and 85.96% in the control group,there was statistically significant difference on the clinical efficacy between the two groups (P<0.05). ③Compared with treatment before,the proportion of gram-positive(G+)bacteria was increased in both groups after treatment (P<0.05),while the proportion of gram-negative(G-)bacteria and spirochete and the bacteria value were decreased in both groups after treatment(P<0.05). After treatment,there were statistically significant differences on the proportion of G+,G- and spirochete and the bacteria value between the two groups (P<0.05). ④Compared with treatment before,the levels of ESR and CRP were decreased in both groups after treatment (P<0.05). After treatment,the levels of ESR and CRP in the treatment group were significantly lower than those in the control group (P<0.05).  Conclusion:Sanhuang Jiedu Decoction combined with metronidazole shows good efficacy in the treatment of acute pericoronitis,which can significantly improve the clinical symptoms of patients,regulate the periodontal microflora and control the inflammation.