Objective:To investigate the therapeutic efficacy and mechanism of Huanglian Jiedu decoction in treatment of perianal abscess of severe type. Method: Patients with perianal abscess of severe type received operation in hospital were divided into two groups randomly, treatment group (n=30) took Huanglian Jiedu decoction orally on the basis of routine therapy after operation, control group (n=26) only received routine therapy. The body temperature, red and swollen around cut were observed. The level of white blood cell (WBC), serum endotoxin(ET), tumour necrosis factor α (TNF-α) of two groups before treatment and on the third day after treatment were tested. Result: There were no significant differences in all data before treatment between two groups. The body temperature and the number of WBC in treatment group was lower than those in control group on the third day, but there was no statistical difference. The degree of red and swollen around cut, serum ET, TNF-α on the third day after treatment in treatment group were lower than those in control group (P<0.01). Conclusion: Huanglian Jiedu decoction is an effective method in treatment of perianal abscess of severe type, which plays a therapeutic action through reducing serum endotoxin and down regulating the level of TNF-α.