Based on the soil temperature data collected at the soil site covered with broomcorn millet over the Loess plateau during the period from August 21 to 23,2005,we calculate the thermal diffusivity (2.950×10^-7～3.015×10^-7m²·s^-1) and the liquid water flux density (1.738×10^-6～2.197×10^-6m³·s^-1·m^-2) via the method of coupled thermal conduction and convection transfer at the depths 0.05m to 0.1m in this area.The soil temperatures are therefore modeled by using the method of coupled thermal conduction and convection transfer,as well as the traditional method of thermal conduction alone.The result shows the latter overestimates both the amplitude (0.42K) and phase shift (0.1407 rad) of soil temperature,and the covariances of two schemes are 2.99 and 2.14,respectively,because it does not consider the soil water vertical movement,while the covariance of the former is 2.13,which makes a reasonable estimate of soil temperature.