Abstract: In order to analyze high temperature resistance of nectarine and provide foundation for high temperature tolerant variety breeding, the grafted nectarine seedlings of‘Zaohongzhu’were used as materials to study the changing tendency of morphological characteristics and physiological indices under different high temperature stresses. The results showed that the injury indices increased with the rising of the temperature, little influence was found under 33 and 39℃, the symptoms of high temperature stress were obvious under 45℃ for 3 consecutive days. The physiological indices of plant changed regularly under high temperature stress, the contents of Chl and Car decreased with the temperature rise, and the descending range increased with the sustaining of the stress. MDA content showed a slightly increase- decrease- increase trend except at the initial stress stage. Pro content increased gradually, but decreased sharply under 45℃. SOD activity kept a slow increase, the activity increased with a small range except on the 3rd day under 45℃. CAT activity increased at first and then decreased, and reached a peak at 39℃. The plant injury indices were significantly correlated with Chl, Car, MDA, Pro, SOD and CAT under high temperature stress.