Abstract: It is well known that the atmosphere exerts influence on mechanical properties of soil.The aim of this paper was to investigate the factors influencing climate.The theories proposed by Wilson(1994) were adopted to describe the fundamental behaviors of temperature and variation of suction of soil.The Darcy’s law and Fick’s law described the flows and evaporation of water respectively.Some proposed assumptions including the characteristic curve of volumetric water content and hydraulic conductivity were only related to the suction of unsaturated soil.The coefficient of latent heat for water was a linear function of temperature;and the heat conductivity was calculated according to the equation proposed by De Vries.The influence of climate factors was also studied by considering rainfall,temperature and wind speed,and the evaporation rate was evaluated by Penman’s equation.The above theory was adopted to simulate the in-situ results of Boissy in France,and the numerical simulation showed that the theoretical and monitored results were in good agreement.