Abstract: In this article,62 cases of psoriasis were treated with Indirubin and another 24 cases with ethylene diamifie tetieacetylimide.The effective rate of lndirubin was 82.26%,while that of ethylene diamine tetreacetylimide was 50%(P<0.025).The main side-effect was the disturbance of digestive system,such as dysentery-like feces; abdominal pain etc,which map subside within 2-4 weeks spontaneouslp.The therapeutical mechanism of Indirubin was investigated preliminarily by determination of velocity and amount of blood flow and that of cAMP and cGMP,but further study should be made.