[Objective] The dynamic change characteristics of carbon density of arbor forest in Tianshan Mountains were analyzed, in order to provide scientific basis for accurate estimation of forest carbon storage and sustainable development in the future.[Methods] Based on the plots of arbor forest in Tianshan Mountains of Xinjiang area, that were investigated every five years from 2001 to 2016, the variation and related factors of carbon density of arbors in this region were analyzed statistically.[Results] From 2001 to 2016, the carbon density of arbor forests in the Tianshan Mountains of Xinjiang area increased with different degrees:the central part of Tianshan Mountains > the west part of Tianshan Mountains > the east part of Tianshan Mountains, and the carbon density change rate was higher in the central part of Tianshan Mountains than in the east part of Tianshan Mountains than in the west part of Tianshan Mountains. From the perspective of forest age, the carbon density of arbor forests in the central and Eastern Tianshan Mountains showed a trend of first rising and then falling with forest age, and the near mature forests had the highest carbon density. In the Western Tianshan Mountains, the carbon density rate showed an increasing trend with forest age. With terrain changes, the carbon density increased first and decreased afterwards with slope degrees. In the Western and Central Tianshan Mountains, the carbon density was the highest in the steep hill. And in East Tianshan Mountains, the highest carbon density was in gentle slope. With the increase of elevation, the carbon density increased first and decreased afterwards in the western and central parts and decreased in the East Tianshan Mountains. With the change of slope orientation, the carbon density in the south slope was the lowest, and no obvious pattern in others.[Conclusion] Since the implementation of Natural Forest Protection Project, the arbor carbon density increased in Tianshan Mountains, and the forest age has the most significant effect. Therefore, in order to improve the carbon sequestration function of natural forest in Tianshan Mountains and explore the greater carbon potential, we should strengthen the regeneration of young forest, optimize the structure of forest age, and promote the healthy and sustainable development of forest resources.