Under various vertical stresses and number of geogrids layers，three types of geogrids were used，respectively，and 30 groups of simple shear tests were conducted on geogrids reinforced sand to study the change of shear behavior of soil. The three geogrids used were rectangular and elliptical bidirectional geogrids along with a tridirectional geogrids. The experimental results show that the thickness of the ribs and nodes as well as the relative opening area positively correlated with the shear resistance while the length and width of ribs negatively correlated with the shear resistance. Besides，the number of layers of geogrids influenced the mechanical properties of sandy soil. The strength decreased when geogrids were added with their laying directions corresponding to the shear direction. The shear failure surfaces were in the upper part of the specimens while in the lower part showed small relative displacement. Meanwhile，the cohesion appeared but friction angle reduced. Therefore when adding geogrids to the same direction with the shear direction of sandy soil will result in a weak soil-geogrid interface，and thus the shear strength decreases. However，the reinforced sandy soil shows an apparent cohesion due to the restriction from the geogrids to the sand.