A new estimation method of soil thermal conductivity, slab method, was presented, which measures the soil thermal conductivityin one-dimensional steady heat conduction process. Compared with the conventional methods, the new method has many advantages, such as convenient specimen preparation, less interference factors, higher measuring accuracy and lower cost. Using this method, thethermal conductivities of two typical soils with different water ratio and dry density were tested. The soil thermal conductivity increases with the increasing dry density and water ratio. The variation curves of the soil thermal conductivity obtained in the experiment is well consistent with those of thethermal probe method. An empirical equation of the soil thermal conductivity and water ratio was derived by curve fitting based on the experimental results, and it is convenient for engineering application．