Abstract: Soil samples were taken from the typical sites in loess area of Shaanxi Province. Freezing test was conducted with the soil samples of different moisture content and dry density to explore the frost heave law of loess under freezing temperature. The results show that Shaanxi loess samples in dry state did not have or little frost heave. The frost heave of loess increased with the moisture content, With the decrease of the freezing temperature, the frost heave decreased gradually and eventually became constant. When the moisture content is low, freezing temperature effect on the dry density of loess sample was not obvious. With the increase of moisture content, the smaller the porosity, the more significant effect on the loess samples under the high moisture content. When the moisture content is low, frozen loess showed shrinkage, under moderate moisture content,the frost heave increased slightly, and under high moisture content the frost heave increased obviously. In the process of freezing,the frost heave force made the intergranular contacting points increase and the proportion of large pores in loess decrease, resulting in increases of the internal friction angle in loess, the lower the freezing temperature, the greater the moisture content, the greater the internal friction angle. The growth of ice crystals destroyed the connection and weakened loess structure, decreased cohesion force. The greater the moister content, the smaller the porosity, the greater impact on the loess cohesion.