Using the surface and 0.40 m depth soil temperature in Jinta oasis as boundary condition, the temperatures at 0.05, 0.10 and 0.20 m depthes were calculated by a one dimensional soil thermal diffusion equation. Comparing with the calculated and observed results on these three levels, it was found that the most significant difference between them appeared at 0.05 m level. Then, based on the characteristic of soil water content variability, evaporation and condensation (EC) processes were considered by improving the former thermal diffusion equation, and more realistic results were obtained, which means the EC processes might be important for hydrothermal variability of soil in Jinta oasis. The affection of EC on the surface energy balance were analyzed based on the observation of energy flux in the local surface. Two phenomena were found: Firstly, from 08:00 to 12:00, the shallow soil heat storage was not totally caused by the net radiation, but partly by the vapor condensation there; secondly, the latent heat flux was abnormally large from 12:00 to 16:00, made the surface energy flux unbalanced at that time, which can be explained as the vapor flux from deep soil being wrongly involved into the vapor flux of surface.