Objective To study the therapentic effect and the possible mechanism of artificial liver support system（ALSS）on patients with chronic severe hepatitis. Methods Forty-two patients with chronic severe hepatitis was treated with artificial liver support system. The liver function, prothrombin time（PT），serum tumor necrosis factor alpha （TNF-α）, endotoxine, nitrogen monoxide（NO）and the side effects were observed. The control group consisted of 43 similar patients treated with the conventional therapy. Results After treating with artificial liver support system, the clinical symptoms of the 42 severe hepatitis pationts were ameliorated. The serum albumin levels increased obviously （P<0.005）. The levels of AST, plasma PT, serum chloridion, total bilirubin, TNFα, endotoxine and NO decreased significantly (P < 0.05 ～ 0.001). Survival rate in the treating group is 50.0% (21/42), while 20.9% (9/43) in the contral group(P < 0.01). The incidence of adverse reaction was 28.6%. Conclusion Artificial liver support system can effectively improve the clinical symptoms and the biochemical indicators, and significantly decrease the levels of pathologic components such as TNF-α, endotoxine and nitrogen monoxide. It can also increase the survival rate, the curative effect of alss was more predominant in earlier patients. Artificial liver support system is an effective and safe treatment of chronic severe hepatitis. 