As an important ecological barrier and water conservation area for the capital, the ecological conservation area plays a key role for Beijing to achieve green development and ecological protection. In this paper, we used an ecological assets model modified by NPP, precipitation, soil and water conservation data to estimate the ecological assets and analyze the spatio-temporal variations of Beijing's ecological conservation area in 2000, 2005, 2010, and 2015. Panel fixed effect regression and quantile regression based on grid scale data were used to test the driving factors of the spatio-temporal pattern of ecological assets. The results showed that: (1) the four periods of ecological assets in Beijing's ecological conservation area showed a trend of rapid growth and then a slow decline. The growth rate of ecological assets reached 133.81% in 2005, dropped to 44.45% in 2010, and changed to -11.02% in 2015. The value of the forest ecosystem accounted for more than 70% of ecological assets in Beijing's ecological conservation area for a long time, which was important for ecological conservation and protection, but its share in 2015 dropped by 3 percentage points compared with that in 2010. From 2000 to 2015, the value of climate regulation, soil conservation and hydrological regulation functions was always higher than that of other ecosystem services. (2) the annual average precipitation had a vital role in promoting ecological assets. The increase of annual average temperature had a significant inhibitory effect on the ecological assets at 10% and 25% quantile levels, while a positive role in promoting the ecological assets at 75% and 90% quantile levels. When the degree of hemeroby was stable within a certain range, it had a significantly positive effect on ecological assets. The increase of population per unit of pixel space had a blocking effect on ecological assets, while the increase of GDP per unit of pixel space had the opposite effect on ecological assets. (3) In terms of the influence of topographic factors on ecological assets, the ecological assets of steep slopes and slopes were above 36 billion yuan per year, which were much higher than those of other slopes. The area of the southern slope was the largest, and its annual ecological assets accumulation was the highest, reaching 18.34 billion yuan, followed by the northeast slope, with an annual ecological value of 14.95 billion yuan. Moreover, the low mountain and hilly areas accounted for up to 71.45%, the annual average value of ecological assets was much higher than other regions.