Abstract: The response sensibility, salt tolerance and photosynthetic characteristics of six major afforestation tree species in Xinjiang, i.e., Populus alba var. pyramidalis, Eleagnus angustifolia, Populus euphratica, Hippophae rhamnoides, Fraxinus chinensis and Ulmus pumila were studied under salt stress conditions. The results showed that the sensibility to salt stress of the six tree speices with different salt concentration was ordered as: Fraxinus chinensis > Ulmus pumila > Populus euphratica > Eleagnus angustifolia > Populus alba var. pyramidalis > Hippophae rhamnoides. Whereas the tolerance duration to the salt stress was ordered as Populus alba var. pyramidalis > Hippophae rhamnoides > Eleagnus angustifolia > Fraxinus chinensis > Ulmus pumila > Populus euphratica. The tolerance duration of Populus alba var. pyramidalis under the highest salt concentration was the longest. Integrating the mortality rate with the minimum lethal salt concentration of each tree species, it was indicated that the salt resistant capacity of the six tree species was ordered as Populus euphratica > Hippophae rhamnoides > Eleagnus angustifolia > Populus alba var. pyramidalis > Ulmus pumila > Fraxinus chinensis. The six tree species could be divided into 3 categories according to the variation pattern of photosynthetic characteristics. Hippophae rhamnoides belonged to the first category whose net photosynthesis rate(NPR) dropped obviously under salt stress compared to the control. Fraxinus chinensis and Ulmus pumila belonged to the second category, showing certain resistance when the salt concentation was under 0.276%. The NPR began to drop along with the increment of salt concentration. Populus alba var. pyramidalis, Ulmus pumila and Elaiagnus angustifolia were divided into the third category, whose NPR increased under salt stress when the salt concentration was below 0.414% and the NPR value could maintain higher than that of the control in certain period of time when treated with certain salt concentration. On the 4th day treated with 0.138% of salt stress, the photosynthetic abiltiy of the six tree species was in the order as Populus alba var. pyramidalis > Hippophae rhamnoides > Populus euphratica > Eleagnus angustifolia > Ulmus pumila > Fraxinus chinensis. The photosynthesis of the six tree species under salt stress was usually decreased significantly compared with the control, whereas the decline amplitude of the photosynthesis ability was ordered as Hippophae rhamnoides > Populus alba var.pyramidalis > Eleagnus angustifolia > Populus euphratica > Ulmus pumila > Fraxinus chinensis.