This study was aimed to explore the sand-fixing mechanism of the mixing soil with Feldspathic Sandstone and Sand in the Mu Us Sand Land. This paper analyzed the texture of Feldspathic Sandstone and Sand, holding water retention, soil crusts and freeze cap using combination technical methods of experiment, simulation and field observation. The results showed that: (1) sandstone and sand distribution ranges were 0.317～709.0 μm and 0.564～2 000.0 μm respectively, when mixed, that could expand the sand composition, improve the texture of sand and surface roughness;(2) The moisture content of the sand reduced rapidly when it changed over the time, it could be reduced from 15.90% to 3.26% within 54 h, and the moisture content of the Feldspathic Sandstone, mixture with Feldspathic Sandstone and Sand were 21.39% and 15.87%, the rate of moisture content declined slowly. The capillary porosity of Feldspathic Sandstone was higher than it of sand. When the Feldspathic Sandstone and sand were mixed, they could improve porosity of sand and reduce the saturated hydraulic conductivity. So, the Feldspathic Sandstone improved water retention properties of sand;(3)Under the action of water, it formed physics crust on the surface quickly after the Feldspathic Sandstone and sand mixed, but it was difficult to form at the anhydrous state. There was significant effect on the thickness of crust formation at the different ways of mixing proportions crust formation. The formation of sandy crust effectively prevented the occurrence of sand dunes and sand flow, so it achieved the role of sand fixing.