This book, starting from the system of human body-close-building-environment, illustrates the impact of thermal environment on the comfort, health and work efficiency of people comprehensively and systematically. The main content: body temperature and temperature regulation system; physical parameter and comments on thermal environment; heat exchange of human body and surrounding environment; thermal comfort of people in medium thermal environment; physiological reaction of people in cold environment; the impact of cold environment on peoples work efficiency; comments on cold stress; physiological reaction of people in hot environment; the impact of hot environment on peoples work efficiency; comments on hot stress; determination of body physiological parameter; thermal comfort of people in dynamic thermal environment; body outdoor thermal comfort; sleeping bag thermal comfort and so on.