Abstract: The surface vibrating compactor is a method to measure the maximum dry density of the coarse grained soil, which is recommended by relevant testing standard codes. However, some parameters for surface pressure and vibrating time are determined by referring to some foreign standard codes, and the research on this area can almost not be found at home. The dry density of two kinds of coarse-grained soil is determined by using the surface vibrating compactor to investigate the influence of vibrating time and surface pressure on dry density. The test results indicate that the dry density and the relative density of the coarse-grained soil become bigger and the amplification reduces gradually with testing time. When the vibrating time is six minutes, the dry density and the relative density basically reach the maximum and tend to be stable. The tests of dry density under different surface pressures show that both the dry density and the relative density of the coarse-grained soil increase with the increase of surface pressure, but the amplification reduces gradually.