Objective To investigate the analgesic effects of intraperitoneal lithium chloride injection on radicular pain behaviors in rats.Methods Using rat model of radicular pain induced by chronic compression of dorsal root ganglion(CCD) ,40 male SD rats were randomly divided into model group and Sham-operation group (group S, n= 12) of radicular pain were established.The rats in the model group were subdivided randomly into Control group(group C, n= 12) ,Early treatment group(group E, n=8) and Later treatment group(group L, n= 8 ).Rats in group E were intraperitoneal injected with lithium chloride once daily on day 2 ～ 4 after CCD respectively,while rats in L,group C and S treated with Vehicle(0.9% NaCl).Rats in L group were intraperitoneal treated with lithium chloride on day 12 ～ 14 after CCD respectively,while rats in E,group C and S received Vehicle.The pain ethology indexes such as paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were tested on day 1 before operation and day 1,4,7,10, 14, 17 and 21 after operation.Results Compared to S group and preoperative level, PWMT and PWTL decreased at Day 1 postoperative in group C (P＜0.05).At day 4 after the operation,compared with group C(7.712 ±0.237)g and (8.190 ±0.382) s,PWMT and PWTL of E group increased to ( 14.607 ± 0,280) g and ( 19.940 ± 0.933 ) s (P ＜ 0.05 ) after intraperitoneal injected lithium chloride.At day 14, compared with group C ( 6.788 ± 0.331 ) g and ( 7.301 ± 0.481 ) s, PWMT and PWTL of group L increased to ( 11.700 ± 0.379) 8 and ( 18.524 ± 1.060) s (P ＜ 0.05 ).This analgesic effect of lithium chloride continued to exist at day 21.However, there was still a significant difference between S group and E,group L(P＜0.05).Conclusion Intraperitoneal lithium chloride injection alleviates pain behavior on radicular pain in rats.