Abstract: Objective To study the analgesic effects and side effects of Centipede-scorpion (CS) powder in mice so as to provide the experimental basis for efficacy-toxicity correlation. Methods Male Kunming mice were randomly divided into 4 groups:saline control group (group NS) and CS 20 mg/kg (group C₁), CS 50 mg/kg (group C₂) and CS 80 mg/kg (group C₃), receive different doses of CS or NS for 4 days by gavage. The acetic acid writhing tests were adopted to observe analgesic effect by recording the mice writhing times. The rotarod performance test was used to examine the sensory and motor coordination of mice. Autonomic activity test was used for detecting the functional status of the central nervous system in mice. The levels of ALT and AST in serum were tested to evaluate its hepatotoxicity. Results Compared with the control group (20.3±5.3), the times of writhing was decreased in CS group (11.8±6.5, 7.6±5.7, 4.1±2.8, respectively), inhibition rates of analgesic were 41.9%, 62.6%, 79.8%, respectively, and the analgesic effect was dose-dependent (P<0.05). Compared with the control group, the average of the behavior of sensory and motor times in the rotarod performance test and autonomic activity test, were decreased in high-dose groups (P<0.05), the average of autonomic activity times were increased significantly in high-dose groups (P<0.05). Compared with the levels of ALT (30.3±5.3) and AST (19.5±3.7) in the control group, hepatotoxicity test showed that the activities of ALT (43.9±6.8) and AST (32.8±5.8) in serum were increased in C₃ group (P<0.05). Conclusion Centipede-scorpion powder had analgesic effect on experimental mice, and at the same time, accompanied by neurological damage and hepatotoxicity in high- dose group.