Habitat quality is an important indicator reflecting regional biodiversity. The scientific planning and effective management of the protected areas play an important role in maintaining habitat quality. In the current study, we evaluated the spatial pattern and temporal dynamics of the habitat quality in Tianjin in 2000, 2005, 2010, 2015 and 2018 by InVEST-Habitat Quality model. Then we compared such pattern changes inside and outside the nature reserve to discuss the role of Nature Reserve in maintaining regional habitat quality. The results show that:(1) from 2000 to 2018, the overall habitat quality in Tianjin decreased by 13.18%, showing an obvious trend of diffusion from the central urban area to the periphery. The higher-quality area only accounted for 4% of the land area, which mainly distributed in the north mountainous areas and wetlands such as Yuqiao Reservoir, Tuanbowa, Beidagang, and Dahuangbao. (2) The spatial distribution of Tianjin protected areas was aggregated, covering about 75% of the higher-quality habitat areas and 25% of the high-quality habitat areas. (3) The effectiveness of habitat quality in different types of protected areas were different. Nature reserves, which habitat quality have been significantly improved, were better than other types of protected areas. Habitat quality of 10 protected areas decreased slightly (but lower than the overall decline level). Only the habitat quality of Panshan scenic spot and Ancient Coast and Wetland Nature Reserve decreased higher than the overall average level. (4) The nature reserve played a role in buffering the declining trend of habitat quality in Tianjin. The absolute and relative changes of habitat quality inside the nature reserve were significantly better than those outside the 5 km buffer zone (P<0.1). Therefore, we suggest to improve the management of protected areas, strengthen protected powering, and give full authority to the managers of protected areas.