Leaf area index is a crucial parameter of vegetation structure which provides key information for earth surface process simulation and climate change research on the global and regional scales.Focusing on the meadow steppe in Hulunber,Inner Mongolia,the accuracy of MODIS/LAI product in this region wasanalyzed.Firstly,the in situ LAI data were acquired through six field experiment in 2013,and the regression models between in situ LAI and vegetation indices were established;then,six high resolution LAI maps from corresponding HJ-1A/B CCD were obtained;finally,comparisons between MODIS/LAI products and high resolution LAI images were conducted to reflect the accuracy of MODIS/LAI products.Results showed that MODIS/LAI product can correctly indicate the grassland growth and phenology.However, because of the uncertainty of the input data,uncertainty still exists between MODIS/LAI product and ground situation with a mean absolute deviation of 0.59 m~2/m~2.Results also showed that MODIS overestimates in situ LAI throughout the grass growing season with an average relative error of 40%.At the beginand end of the growing season,a bigger overestimation occurred of MODIS/LAI products because of the surface heterogeneity caused by the soil background,and at the middle of growing season,overestimation decreased with a relative error of 30%.The results are important to understand regional produce accuracyand further improve model predictions of Hulunber meadow steppe.