Abstract: In this paper,the effect of acute heat stress on the level of natriuretic peptide (ANP),angiotensin (AⅡ) and humoral Na+/K+ in mice was investigated.The results showed that there was no significant change of the ANP level in plasma with treatment of heat stress.On the contrary the level of plasma AⅡ and lung index markedly increased,and the Na+/K+ decreased.In recovery stage,the ANP level rapidly increased to 250% of the control,at the same AⅡ content in plasma decreased to 47% of the control,Na+/K+ continuously decreased,the lung index decreased to normal level.These results indicated that ANP and AⅡ were involved in the progress of heat stress and play a key role in regulating metabolism of water and salt,by which body damage is protected and homeostasis were thus maintained.