Objective To observe the therapeutic effects of plasma exchange for patients suffered from gravis hepatitis, and analyze the main factors which influence the results. Methods Ninety-two patients with severe hepatitis were divided into two groups randomly: the treatment group and control group. In the treatment group, the patients were treated with the plasma exchange on the basis of routine medical therapy, but the control group received the routine medical therapy only. The signs such as main symptoms, several blood biochemical data before and after treatment were observed and analyzed for judging the effects. Results The patients' symptoms and liver functions with plasma exchange improved obviously, and the total effective rate was 61.53%. There were significant differences between the two groups for early and middle stage cases. Conclusion Plasma exchange is an effective method for gravis hepatitis, and it may also be used to judge prognosis.