Abstract: Physical composition and microstructure of loess have an important significance to research further engineering geological characteristics, collapsibility and its mechanism. So the physical components such as particles, chemical composition, mineral component, soluble salines and microstructure of leoss along the line of Fuxin-Chaoyang freeway, are tested and analyzed by means of particle analysis, X radial diffract technique, chemical test and scanning electron microscope(SEM). As a result, some conclusions are drawn as follows:①Silt grain is main part in loess, and content of coarse silt is great. The content of clay grain has a larger range. ② The drossy minerals in loess are mainly comprised of quartz and feldspar. Illite and blending of montmorillonite and illite take a dominating position in clay mineral.③ The content of diffluent saline and hardy-soluble saline in loess are less than other areas in China. And ④ the structure loess is looser in shallow depth, and denser in deeper depth. There are weak-cemented structure with bracket particles and big pores and half-cemented structure with bracket particles and big pores to inlay particles and micro pores in cemented structure in deep depth. shallow depth, and flocculent-cemented structure and clotted-cemented structure in deep depth.