The Dunhuang correction site is the most important radiation correction site in China, and the directional reflection characteristic of the ground target is an important parameter affecting the site calibration accuracy. Until now, there are no clear studies on circumstances that necessitate the ground reflectance correction, and which bidirectional reflectance distribution function (BRDF) is used for correction. Due to the high accuracy of medium-resolution image spectrometer (MODIS), MODIS images are analyzed. First, using six sets of unmanned aerial vehicle multi-angle observation data under different sun zenith angles at the Dunhuang site in September 2020, 36 different BRDF models are established by six different kernel function combinations. For the images under different observation angles, we calculated the apparent reflectance before and after the BRDF correction and compared the relative deviation with the measured apparent reflectance of the satellite. By considering the observation angle of 28° as the boundary, the experimental results show that the relative deviation is greater when the angle is greater than 28°, which is a significant consequence of the BRDF correction. Among the BRDF models established above, the BRDF model established using multi-angle observation data measured close to the time of satellite transit has a better correction effect. Furthermore, the relative deviation between the apparent reflectance calculated by the BRDF model using the kernel function combination of Rossthick-Lidense or RossThick-LiSparseR or Rossthin-LisparseR and the satellite observation value are small.