OBJECTIVE To study the improvement effects and mechan ism of thalidomide on Alzheimer ’s disease （AD）model of Caenorhabditis elegans . METHODS In this study ，the BR 5270 strain of C. elegans was used as AD model and BR 5271 strain as the control. The effects of thalidomide （0.5，2.0，6.0，15.0 mg/mL）on the motility of BR 5270 strains of C. elegans were studied by the basal slowing response assay ；the effects of thalidomide （0.5，2.0，6.0，15.0 mg/mL）on the survival time of BR 5270 strain of C. elegans were studied by life assay ；the effects of thalidomide （0.5，2.0，6.0 mg/mL）on learning and memory ability of BR 5270 strain of C. elegans were studied by short-term and long-term learning and memory assay. RT-PCR technology was used to study the effects of thalidomide （0.5，2.0，6.0 mg/mL）on mRNA expression of phosphatidylinositol 3-kinase（PI3K）/protein kinase B （Akt）signal pathway related genes （Age-1，Akt-1，Gsk-3）and calpain homologous gene （Clp-1）in BR 5270 strain of C. elegans . RESULTS After the intervention of thalidomide ，oscillation times of BR 5270 strain of C. elegans increased significantly within 30 s （except for 0.5 mg/mL group ），and the 10％ of maximum life span was prolonged significantly （only 0.5 mg/mL group ）；the short-term and long-term learning indexes were improved significantly （only 6.0 mg/mL group ）；mRNA expression of Age-1 and Akt-1（except for 0.5，2.0 mg/mL groups ）were increased significantly ，mRNA expression of Gsk-3（except for 0.5 mg/mL group ） and Clp-1 were decreased （P＜0.05 or P＜0.01）. CONCLUSIONS Thalidomide can ameliorate the dyskinesia of AD model of C. elegans，prolong the lifespan of this strain ，and enhance its learning and memory ability. Its mechanism of action may be related to activation of PI 3K/Akt signaling pathway and inhibition of calpain.