Abstract: 【Objective】 aboveground biomass at different time and spatial scales and analyze its influencing factors, this project aims to reveal the dynamic change process of the ecosystem in the natural forest area and explore the environmental factors affecting the change of aboveground biomass. 【Methods】 Based on the remote sensing data of the past 20 years from 2000 to 2022 and the actual sample data of the forest land in the study area, this study used the remote sensing information to establish an estimation model, estimate the aboveground biomass in the typical natural forest area of Tianshan Mountain, Xinjiang, and analyze the temporal and spatial dynamic changes of biomass in the area and the influencing factors of the aboveground biomass changes of natural forest lands. 【Results】 The spatial distribution of aboveground biomass in woodland in the study area was obvious, with high biomass in northeast China and low biomass in southwest China, mainly concentrated in the northern part of the study area. In 2022, the forest biomass of the Internship Forest Farm was about 3.728×10⁶ t, the maximum value was about 559.67 t/hm², and the average biomass was about 233.45 t/hm². The biomass in the northeast was higher than in the southwest, and the increase in latitude led to a decrease in biomass. There were differences in the interannual variation trend of aboveground biomass in woodland in the study area, and the overall state was stable and growing, with 52.63% of the area biomass increasing and 47.37% of the area biomass decreasing. The biomass per unit area of different forest age stages increased with the increase of forest age, and the biomass of the tree layer was the highest in mature forests. 【Conclusion】 In the forest land in the study area, the area and biomass proportion of juvenile forest to overmature forest are different, and it is necessary to increase the investment in natural regeneration and artificial tending work. From 2000 to 2022, the aboveground biomass of forest land in the study area gradually increased from north to south, and precipitation played a positive role in biomass growth. In the southwest area of the Internship Forest Farm, human activities are frequent, and changes in temperature and precipitation affect the growth of trees and grasslands, resulting in the high distribution of biomass in the northeast and low distribution of biomass in the southwest.