Objective To explore changes of plasma noradrenaline (NA), adrenaline (ADR), atrial natriuretic peptide (ANP) levels, and plasma renin activity (PRA) at acute exposure to 4500m altitude and their significances. Methods A set of hypobaric chamber was applied to simulate 4500 m altitude. Venous blood samples of 43 healthy young males were obtained before and at 22 hours after acute exposure to simulate 4500 m altitude. High-performance liquid chromatography-electrochemical method was used to detect plasma NA and ADR concentrations, while plasma ANP concentration and PRA were detected by radioimmunoassay. Subjects whose scores were higher than 10 were allocated into acute mountain sickness (AMS) group, and those less than 10 into non-AMS Group. Results After acute exposure to high altitude, concentrations of plasma NA and PRA significantly decreased[NA: (3.7±0.8) vs (2.9±0.5) ?g/L; PRA: (2.9±1.8) vs (1.3±1.1) ?g/(L?h); P＜0.01], however plasma ADR, ANP concentrations significantly increased[ADR: (2.0±0.6) vs (2.5±0.5) ?g/L, P＜0.01; ANP: (79±31) vs (100±42) ng/L, P＜0.05]. Plasma NA concentration was significantly higher in AMS group than in non-AMS group after exposure to 4500 m altitude[(3.1±0.4) vs (2.8±0.5) ?g/L, P＜0.05], although it was not different at plain. AMS score was positively correlated with plasma NA concentrations either at plain or at 4500 m altitude（r = 0.435, 0.391, P＜0.05）. Conclusion Apparent nerve-endocrine changes occur at acute exposure to high altitude, and these changes may be related to AMS.