The purpose of this study was to examine the effects or prolonged Dinghy Yacht Sailing Training on Thermoregulatory Responses during absolute exercise intensity. The subjects of this study were divided by two groups; Dinghy Yacht Sailing(Yacht Group ; YT) was 10 Yacht players and Untrained Group(UT) was 10 university students. All subjects participated in VO₂ max test and absolute exercise workload(treadmill belt speed : 8.3 km/h for 40 min). In the rectal temperature, there were increased during exercise at both YT and UT groups, and YT group were higher than that of UT group. Also there were significant difference at the end of exercise and 24 h post(p＜.05). In the blood norepinephrine concentration there were increased both YT and UT group during exercise. And YT group were higher than that of UT group at the end of exercise, rest level, and 24 h post and there were significant difference between groups(p＜.05). In the blood epinephrine concentration there were increased both YT and LIT group during exercise. And YT group were higher than that of UT group resting level and at the 24 h post. So there were significant difference between groups(p＜.05). In this study, prolong training at the cold environments make a increase the hormonal adaptation response, especially norepinephrine secretion and might be modified the body thermoregulatory mechanism that monitors changes the external environments. Also, increased capacity of the thermoregulatory may improve the body`s overall production of hormonal adaptation related to heat production metabolism which may or protection against cold injury.