Long-term dynamic monitoring of the Net Primary Productivity (NPP) and carbon sequestration capacity of the ecological management project area using remote sensing data can evaluate the implementation effect of the management project and provide strong support for the realization of the carbon neutrality goal and sustainable development of the area. In this paper, we used Google Earth Engine (GEE) platform to calculate the NPP of the Beijing-Tianjin sandstorm-control project area based on the improved CASA model. The spatial and temporal changes of NPP during 2001-2020 were analyzed using Sen slope analysis and MK trend analysis, and the response of NPP to the implementation of the Beijing-Tianjin sandstorm-control project was analyzed. The results showed that: 1) during the period of the Beijing-Tianjin sandstorm-control project, the NPP in the Beijing-Tianjin sandstorm source area presented an overall fluctuating upward trend with an average growth rate of 2.21 gC m^-2 a^-1, among which 38.03% was highly significant increase, indicating that the Beijing-Tianjin sandstorm-control project has played a positive role in China's carbon neutral task and increased the carbon sequestration capacity of the area; 2) On the spatial scale, the NPP and carbon sequestration in the Beijing-Tianjin sandstorm source area were spatially heterogeneous, and the spatial distribution was mainly characterized by high in the east and low in the west, among which the warm temperate deciduous broad-leaved forest region was the highest, and the temperate desert region was the lowest; 3) The rate of NPP growth brought by the implementation of the control project was not consistent in different regions, and the rate of NPP growth from 2001 to 2020 in Beijing-Tianjin-Hebei region (4.74 gC m^-2 a^-1) > Shanxi region (4.52 gC m^-2 a^-1) > Shaanxi region (3.53 gC m^-2 a^-1) > Inner Mongolia region (1.55 gC m^-2 a^-1); 4) The improvement of the ecological environment brought about by the implementation of ecological projects was generally characterized by slow and then fast changes, with the rate of change in the latter decade being significantly greater than that in the first decade in most regions. In Inner Mongolia, where the ecological environment is relatively harsh and the desert area is widely spread, the ecological environment improvement had a certain lag, with the growth rate of NPP only 0.04 gC m^-2 a^-1 from 2001 to 2010, and only in 2011 did the NPP start to increase more significantly, with a growth rate of 1.67 gC m^-2 a^-1 from 2011 to 2020. Therefore, the ecological project needs long-term persistence to achieve more obvious results.