Abstract: To investigate the effects of drought on NPP (Net Primary Productivity) in the Xilingol grassland, this paper used the 12-month Standardized Precipitation Evapotranspiration Index (SPEI) and MODIS MOD17A3 NPP data from 2000 to 2020. The temporal and spatial variation characteristics of drought and NPP were analyzed based on the Theil-Sen trend analysis and Mann-Kendall nonparametric test, and the correlation analysis method was used to assess the impact of drought on NPP in the Xilingol grassland. The results showed that the climate of the Xilingol grassland is humid, particularly in its eastern part. NPP showed an increasing trend and a decreasing trend from northeast to southwest. In space, SPEI is mainly positively correlated with NPP, with an area of 99.88%, indicating that vegetation conditions tended to improve with drought relief. Temporally, SPEI was significantly positively correlated with NPP in all vegetation types, with the strongest correlation observed in typical steppe. Drought occurrence will cause NPP loss, which will increase with increasing drought intensity and area. These research results can provide a scientific basis for investigating climate change, disaster relief, and other issues.