Abstract: At present, habitat quality is under constant threat due to the impact of human activities. Therefore, it is particularly important to assess habitat quality status and trends. In this study, the Habitat Quality module of InVEST model was used to analyze the impact of unused land development on habitat quality in Tang County, China in 2000, 2007, and 2016. The results showed that 1) from 2000 to 2016, the development direction for unused land was mainly grassland, forest land, and cultivated land. The proportion of unused land decreased from 100% (based on the unused land area in 2000) to 33.70%, whereas the proportion of grassland, forest land, and cultivated land increased from 0% to 27.43%, 21.30%, and 10.46%, respectively. 2) The proportion of unused land patches in the landscape area of Tang County decreased year by year. The average patch area decreased from 94.73 hm² before development to 6.15 hm² after development, and the forest land, water area, and grassland proportions in the landscape area increased. Furthermore, the evenness and diversity indexes increased after the unused land was developed and ecosystem stability improved. 3) After the exploitation of unused land, the habitat quality in the study area significantly improved, and the habitat quality score increased from 0.09 in 2000 to 0.28 in 2007, and then to 0.39 in 2016. The habitat quality high value areas were mainly located in the middle of the study area and northwest of Qijiazuo Town, the southern part of Huangshikou Town and the northern part of Yangjiao Town. However, the habitat quality in Chuanli Town, Juncheng Town, and Luozhuang Town, and in the southern region was lower. This study analyzed the impact of unused land development on habitat quality, and the results provide a scientific basis for making reasonable land planning decisions and for protecting habitat and biodiversity during land development.