Energy expenditure of five young adults worked in the hot desert environment were measured by the methods of indirect calorimetry in the Wuwei Gansou in July 1989.The results indicated that the basal metabolism rate, the resting metabolism rate and the energy cost of young adults marching in the desert and Gobi (15kg load, at rate of 3.5km/h) were 2.782,3.059,14. 188, 10.305 kJ? m-2?min-1 respectively. It was shown that under the similar conditions energy expenditure marching in the desert was 38% more than in the Gobi.Ambient temperature had a greater effect on energy expenditure but the effect was various at different activities. When at 24.5-38.4℃ during marchi-ng(15kg load),1℃increase in ambient temperature was associated with anincrease of about 0.86% energy consumption. While at 25-33℃ during quiet rest the energy consumption tended to decrease with an increase of ambient temperature. But at 33-40℃ it increased with ambient temperature again. It is suggested that the energy metabolism may be more easily influenced by ambient temperature when the metabolic heat production of human body is increased.The present study recommended the estimation of energy requirement for the adult with a moderate activity in hot desert environment should be approximate 15.062MJ/d