By using soniscope, the wave velocities in depth of 0 to 1.5 m of seasonally frozen ground at four geomorphic units in Lanzhou are obtained during the winter and the soil density, moisture content and ground temperature are measured respectively. Relations between the wave velocity and the cementation of soil, ground temperature and moisture content are analyzed. The results show that the cementation of soil has an important effect on the wave velocity. The better the cementation of soil, the greater the wave velocity. When the temperature of soil is above 0℃, wave velocity decreases with the increase of moisture content. When the temperature is below 0℃, wave velocity increases with decrease of the temperature of soil.