Objective To investigate the effects of intraperitoneal injection of dexmedetomidine (Dex) on the memory and pain threshold in rats with sleep deprivation.　Methods　Ninety adult SD rats were randomly divided into three groups (n=30): a control group (group C), a group of sleep deprivation (group SD) and a group of sleep deprivation with Dex (group SD+D). The rats in groups SD and SD+D were placed on a glass platform within a tank filled with water, 10 h per day for 8 consecutive days. Meanwhile, those in group C were placed on a glass platform within a tank without water. Rats in group SD+D was intraperitoneally injected with 50 μg/kg Dex once a day, while those in groups C and SD were given the same amount of normal saline. Morris water maze positioning navigation behavior test was performed to measure escape latency every day. Then, paw mechanical withdrawal threshold (PMWT) and paw withdraw thermal latency (PWTL) were measured.　Results　Compared with group C, group SD showed obviously prolonged escape latency from day 3 to day 8(P＜0.05). There is no difference in escape latency between groups SD+D and C (P＞0.05). Compared with group SD, group SD+D presented obviously shortened escape latency from day 3 to day 8 (P＜0.05). Compared with group C, group SD showed obviously reduced PMWT and PWTL from day 2 to day 8 (P＜0.05). There is no difference in PMWT and PWTL between groups C and SD+D (P＞0.05). Compared with group SD, groups C and SD+D presented obviously increased PMWT and PWTL from day 2 to day 8 (P＜0.05).　Conclusions　Intraperitoneal injection of Dex can improve the memory of rats with sleep deprivation, and reduce the pain in those rats.