The aim of this research was to quantitatively assess the productivity of Hulunbuir grassland and clarify the impact of climatic factors on the grassland growth processes.Our study used the MOD17A2Hdataset and meteorological data to study the temporal and spatial variation of annual net primary productivity (NPP)and the relationship between NPP and climate factors in the grassland of Hulunbuir,China.We found that the annual mean value of NPP in Hulunbuir grassland gradually decreased from northeast to southwest. The average NPP value for the period 2000to 2017was 307g C·m~(-2),and the NPP during the 18years has increased, with the lowest value being 242g C·m~(-2)in 2001,and the highest value being 372g C·m~(-2)in 2014. The high NPP values(>400g C·m~(-2))are mainly distributed in the eastern and western of Daxing'anling mountainous area with grassland type of lowland meadow;the median NPP values(250-400g C·m~(-2))are mainly distributed in the interlaced hills and high plains with grassland types of mountain meadow and temperate meadow steppe;the low NPP values(<250g C·m~(-2))are mainly distributed in southwest Hulunbuir where the grassland is categorized as swamp meadow and temperate steppe.The NPP of different grassland categories ranked in order:lowland meadow>mountain meadow>temperate meadow steppe>swampy meadow> temperate steppe.Climate change is also observed to be a large influence on NPP interannual variation. The correlation between NPP and precipitation is higher than that between NPP and temperature,indicating that precipitation is the more important contribution to NPP variation in Hulunbuir grassland.The response of lowland meadow and mountain meadow to climatic change is less pronounced than that of temperate meadow steppe and temperate steppe.