Abstract: Since the occurrence probability of heat emergency in the manned space activities is relatively high ,heat stress should be paid more attention to relieve its effects on crewmembers.This paper provided some methods for selection and training of astronaut candidate on the basis of significant relationships between them and capabilities of heat tolerance It is suggested that adaptive index of cardiac function and maximaum oxygen uptake ( O 2 max ) should be used as selective targets and several physical fitness training should be carried out in order to get further improvements of heat tolerance.