[Objective] The changes of habitat quality and its affecting factors in the nature reserve were studied for the formulation of effective local ecological protection policies.[Methods] Taking the Pogang nature reserve in Xingyi City of Guizhou Province as an example, based on the images of Landsat-5 TM, Landsat-7 ETM⁺, Landsat-8 OLI, and combining ArcGIS with ENVI software, we used habitat quality estimation model and habitat quality contribution rate of land use transformation to analyze the land use change and its impact on habitat quality from 1990 to 2017 and to quantitatively assess the effect of the policy of grain for green on the improvement of habitat quality.[Results] The land transformation of reserve mainly occurred from grassland and cultivated land to forest land, and from other land types to grassland and forest land from 1990 to 2017. During the past 28 years, the overall habitat quality of the reserve showed a trend of first increase and subsequent decrease. The increase was by 15.71% in comparison with the value in 1990. The average habitat quality of the reserve in 1990 was ranked as:buffer area > core area > pilot area; whereas the average habitat quality of the reserve after 2001 was the core area > buffer area > pilot area. As the policy of grain for green was carried out, the average habitat quality index of Pogang Nature Reserve increased significantly from 0.88 to 0.92.[Conclusion] The establishment of Pogang Nature Reserve, the implementation of the reforestation project and the increase of human activities are the main reasons for the change of the habitat quality.