Abstract: Objective The gene expression was studied to investigate the molecular mechanism of heat acclimation.Methods Heat acclimation model of rats was made first,then the hypothalamus tissue was isolated from the model rats and the normal ones respectively.The genes expressed differentially between these two kinds of tissue were identified using the differential display PCR technique and confirmed by dot blothybridization of total RNA,then were sequenced and analyzed.Results A piece of cDNA was selected for its higher expression in the hypothalamus of heat acclimated rats and was determined to be a sequence with 164bp.Conclusion The results suggest that genes were differentially expressed in heat acclimated animals compared with normal ones,which may contribute a lot to maintaining their ability of heat adaptation.