Abstract: Objective To compare the classic and exertional animal models of heat stroke. Methods Thirty male SD rats were randomly divided into control group, classic heat stroke(CHS) group, and exertional heat stroke(EHS) group(10 in each group). The rectal temperature, its time to reach 42.5℃, and serum creatine kinase(CK) level were measured. Lesions in their major organs were observed with H&E staining. Results The average onset time of heat stroke was significantly shorter whereas the serum CK level was significantly higher in EHS group than in CHS group(58.333±9.309 min vs 108.333±23.166 min, 4 444.44±1 287.915 U/L vs 1 208.217±192.802 U/L, P<0.01). However, no significant difference was observed in mortality between the two groups(P>0.05).The lesions of major organs(small intestine, kidneys, and skeletal muscle) were significantly severer in EHS group than in CHS group. Conclusion The function of different organs is impaired much rapider and severer in exertional animal model of heat stroke than in classic animal model of heat stroke at its early stage.