The dielectric properties of the actual land surface and snow deposit are described using the four-component model of dielectric constant of soil and the dielectric constant model of snow respectively. The actual rough land surface is simulated with the model of exponential type distribution rough surface and Monte Carlo method, the composite electromagnetic scatterings from the rough land surface covered with snow and the column with rectangular cross-section above it are studied using the finite-difference time-domain method, the curves of angular distribution of composite scattering coefficient are obtained, the bistatic composite scattering coefficient varying with the roughness parameter and dielectric parameter of soil and snow, the geometric parameter and dielectric parameter of the column with rectangular cross-section are calculated in detail. The characteristics of the composite scattering coefficient from rough land surface covered with snow and the column with rectangular cross-section above it are also obtained.