Objective To observe the effect of Baizhu Gradules [Gradules containing Huangbai （Cortex Phellodendri） and Cangzhu （Rhizoma Atractylodis）] on the complication and wound healing after operation of anal fistula of downward flow of damp-heat syndrome in TCM to analyze its functional mechanisms. Methods In the randomize controlled clinical study

60 subjects were devided into a treatment group and a control group. The treatment group （31 cases

1 case excluded later） was administered Baizhu Gradules for oral taking as well as dressing change. The control group （29 cases） was treated with dressing changes everyday. The time of wound healing

wound secretions

and pain scores of the two groups were observed. Results The total clinical effective rate of both groups was 100%. In the treatment group

the averaged wound healing time was （22.64±2.34） days

while in the control group

it was （25.36±2.38） days

the difference was statistically significant （P<0.05）

the wound healing time of the treatment group was earlier than that of the control group. The comparison of wound secretions showed a statistical difference between the two groups （P<0.05）

the score of the treatment group was superior to that of the contrl group. On the 6th day after operation

the pain score of the treatment group was better than that of the control group

however

on the 10th day

there was no statistical difference between the two groups in the pain scores （P>0.05）. Conclusion Baizhu Gradules could effectively absorbing the wound secretions and relieving the postoperative pain

therefore the wound healing is quickened.