In the paper, the three outstanding features of climate change in Xinjiang for the recent 40 years are identified. Their causes are discussed primarily from two aspects of natural change and factitious influence. Results are as follows: (1)The warming trend of winter mean temperature in northern and southern Xinjiang are resulted from the controlling of macroclimate regularities of winter warming in The Northern Hemisphere and the local influence of factitious factors, the former is more important than the latter. (2)The increasing trend of summer precipitation in southern Xinjiang may have little to do with the change of macroclimate background, but mainly have to do with human activities, especially with increasing of real evaporation in oasis area, which are result from both the area under cultivation (or oasis) enlarging continually in southern Xinjiang between the south foot of Tianshan Mountains and the north foot of Kunlun Mountains and the amount of drawing water from Tarim River increasing continually. Furthermore, the warming trend of summer in southern Xinjiang for the recent 40 years coinciding with The Northern Hemisphere also helps to increase evaporation intensity, to form the increasing trend of real evaporation amount, and results in the increase of summer precipitation. But this is less important than the increase of available evaporation water amount and evaporation area that result from the acreage under cultivation (or oasis) enlarging. (3)The variability of annual mean temperature in Tianshan Mountainous area is the greatest, which maybe have to do with that the annul difference of early or later of forming or smelting, thick or thin and cover extent of seasonal stable snow is largely in the area.