In visible spectral band, we measured the BHDF of grass and man-made object similar to grass with three angular sampling intervals in principal plane. Based on the experimental data, we can draw the conclusion： when the sun zenith angle is large （〉 45°）, a interval of 20° is adequate to capture the BRDF of grass in principal plane;when the sun zenith angle is small, a less angular sampling interval in zenith angle is needed in the hot spot area. The above conclusion was not only useful to the selection of angular sampling interval in satellite multi-angle remote sensing but also to reduce experimental work.