Heat stress is an important factor which influences agricultural production. On The basis of advances of studies on heat stress physiology of plant, the paper reviewed the changes of the stability of membrane, antioxidant metabolism, polyamine metabolism, heat protein, photosynthesis and their thermotolerance mechanism. Moreover, responses of ABA, Ca2+, SA, JA to heat stress. Heat stress increases the content of ABA, Ca2+, SA, JA in plants; The same time, external signal molar can enhanced thermotolerance of plants. Further research ideas for signal transduction of heat stress are suggested.