Abstract: 【Objective】 To probe into the differences of photosynthetic characteristics of different introduced Fraxinus in Yili area and analyze the effects of physiological and ecological factors in the hope of providing scientific basis for the introduction, breeding and regional cultivation of Fraxinus chinensis in this area. 【Methods】 The diurnal changes of photosynthesis of eight introduced Fraxinus chinensis seedlings (Lula No.1, No.2, No.3, No.4, No.5, no.6, Red leaf Fraxinus and Fraxinus chinensis 'Aurea') under natural conditions in Yili area of Xinjiang were measured by li-6400xt photosynthetic apparatus. The relationship between different physiological ecological factors and photosynthetic characteristics was analyzed with Fraxinus macrophylla in the same year as control. 【Results】 The eight introduced varieties (lines) of Fraxinus chinensis showed better photosynthetic characteristics than those of Fraxinus rhynchophylla, and the net photosynthetic rate (Pn) of different varieties (lines) showed a single peak or double peak curve; PN of each variety (line) was affected by different physiological and ecological factors, among which stomatal conductance (Gs) was the most important factor, and was negatively correlated with intercellular dioxygen (Ci), and it was negatively correlated with PAR and RH (P<0.05) or extremely negatively correlated (P<0.01). 【Conclusion】 The net photosynthetic rate (Pn), transpiration rate (Tr), water use efficiency (WUE) and local adaptability of the eight introduced Fraxinus chinensis seedlings are higher, and the introduction and domestication of Lula 3 and Lula 6 are the most successful.