The Bidirectional Reflectance Distribution Function（BRDF） of land surfaces specifies the behavior of surface directional reflectance as a function of illumination and viewing angles.The bidirectional reflectance products of the Moderate resolution Imaging Spectroradiometer（MODIS） and the Multiangle Imaging Spectroradiometer（MISR） and their BRDF model parameters products have been available respectively.Since the BRDF model parameters are inverted from limited angular observations for a given pixel

it is necessary to evaluate whether they can effectively characterize the directional reflectance in other viewing directions.In this study

we choose four kinds of land cover types to analyze the representation of MISR and MODIS BRDF model parameters

by comparing the directional reflectance extrapolated using the BRDF model parameters with the observed directional reflectance.The results show that:（1） both MODIS and MISR BRDF model parameters have better representation on directional reflectance at some viewing directions.Especially MISR BRDF model parameters have preferable representations at MODIS viewing directions;（2） the representative ability of both BRDF model parameters tends to weaken when the viewing zenith angle increases;（3） from the analysis of the observed data set shown in this paper

it seems that the representative ability of MODIS BRDF models is better near cross-principal plane than that near principal plane.