Abstract: It is of great significance for regional atmospheric environmental protection and sustainable economic development to study the spatial and temporal pattern changes and influencing factors of PM_2.5 concentration in Beijing-Tianjin-Hebei Urban Agglomeration Based on PM_2.5 remote sensing data, ground station meteorological data, DEM data, MODIS NDVI data, night light data, population density data, land use type data and road network data, Theil Sen Median trend analysis, Mann Kendall significance test and Getis Ord Gi * analysis are used to analyze the spatial and temporal changes and spatial aggregation characteristics of PM_2.5 concentration in Beijing-Tianjin-Hebei Urban Agglomeration, and use Geo-detector to explore the influencing factors of its spatial differentiation.The results show that: (1) PM_2.5 pollution is serious in Beijing-Tianjin-Hebei Urban Agglomeration from 2000 to 2021, and the annual average PM_2.5 concentration is 59.94 μg·m^-3, winter is the high incidence season of PM_2.5 pollution in Beijing-Tianjin-Hebei Urban Agglomeration, but the PM_2.5 concentration in Beijing-Tianjin-Hebei Urban Agglomeration generally shows a downward trend, with a change slope of -0.85 μg/(m³·a). (2) The spatial distribution pattern of PM_2.5 concentration is high in the southeast and low in the northwest, and the area where PM_2.5 concentration decreased significantly accounted for 76.52%, mainly concentrated in the middle and south of Beijing-Tianjin-Hebei Urban Agglomeration. (3) The aggregation of PM_2.5 concentration changes is high in the northwest and low in the southeast. The hot spot area of PM_2.5 concentration changes accounts for 50.95% (4) The factor detection results show that temperature (0.91), elevation (0.81) and road network density (0.63) are the main factors affecting the spatial differentiation of PM_2.5 concentration in the Beijing-Tianjin-Hebei Urban Agglomeration. During the study period, the influence of precipitation on the spatial differentiation of PM_2.5 in the Beijing-Tianjin-Hebei Urban Agglomeration shows an upward trend, while the influence of humidity, sunshine hours, night light and road network density on the spatial differentiation of PM_2.5 in the Beijing-Tianjin-Hebei Urban Agglomeration shows a downward trend The interactive detection results show that temperature plays a very important role in the factor interaction, and the interaction between temperature and precipitation, elevation and road network density is the main factor combination affecting the spatial differentiation of PM_2.5 in Beijing-Tianjin-Hebei Urban Agglomeration The research results showed that the PM_2.5 concentration in the Beijing-Tianjin-Hebei Urban Agglomeration showed a decreasing trend from 2000 to 2021, and temperature, elevation, and road network density played a significant role in the spatial differentiation of PM_2.5 concentration in the Beijing-Tianjin-Hebei Urban Agglomeration.