The uniform model of three kinds of typical grounds, i.e. dry bare ground, wet bare ground and ground covered by low vegetation, was constructed based on the heat balance equation of ground surfave. All kinds of factors were under consideration. In calculation, the Monte Carlo simulation was used to analyze the above natural ground's periodical infrared radiance statistics and the influence on the average value and variance (fluctuation) of the infrared radiation temperature caused by the above circumstance factors. The experimental results show that the model can simulate the infrared radiance statistics of the above typical ground fairly well.