Abstract：Ultrasonic wave velocity traveling in media reflects the physico-mechanical properties of the media. Velocities of the ultrasonic (dilatational and shear) waves in frozen fine sand，silt (loess) and clay with different densities are measured at different temperatures by UVM-2 ultrasonic measuring system. Then，the variation tendency of ultrasonic wave velocities with densities and temperatures is analyzed. The following results are obtained. (1) The ultrasonic wave velocities are influenced by soil particle size and soil composition which affect the variation of the bound water content and then the variation of unfrozen water content after the soil is frozen. Therefore，in terms of the ultrasonic wave velocities versus temperature and unfrozen water content versus temperature， the relationship can be set up between ultrasonic wave velocities and unfrozen water content. (2) The variation of dilatational and shear wave velocities is related to that of densities of soils，especially of frozen loess. (3) Different type of the frozen soil is of different scope of dilatational and shear velocities. The ratio of dilatational to shear velocities which express the relative range of compression and shear can be used to determine the type of frozen soils. Generally，the ratios are 1.07，2.15 and 0.7 for frozen clay，frozen loess and frozen fine sand，respectively. In terms of elastic theory，the Poisson¢s ratio is related to wave velocity ratio，so that the property of strength and deformation can be determined by measuring the velocity ratio.
