To study the connection between SARS (severe acute respiratory syndrome) complicated liver functional injury and hepatitis virus B. We observed 108 cases of SARS patients:38 cases with hepatitis virus B (A group) , 46 cases without any liver diseases (B group) , 24 cases with fatty liver (C group) . Then compared the relationship between the degree of liver injury and the variation of hepatitis virus B. The results showed that the degree of liver injury in SARS patients with hepatitis virus B was higher than that in SARS patients without hepatitis virus B. In the same time, the incidence of complicated severe hepatitis was higher too. The activation of viral wild strains was easier in SARS patients with hepatitis virus B. There was no evident difference between patients with fatty liver and without fatty liver. Therefore, we should observe the liver function of the SARS patients with hepatitis B more carefully, prevent and treat their acute hepatic cell necrosis.