Abstract: Temperatures inside a solar greenhouse vary dynamically throughout the day. A calculation model for temperatures inside greenhouses during a clear day was established in this paper. The boundary conditions were based on solar radiation, sky radiative temperature, external air temperatures, relative humidity, wind velocities and soil temperature at 1.0 m deep inside. Conservation equations were solved using unsteady simulations by Computational Fluid Dynamics technique(CFD) and temperatures inside a solar greenhouse during a clear day were simulated in time and in space. The results show that the simulated air and soil temperatures have the same pattern with the measured ones with the differences between the simulated air temperatures during the night and soil temperatures at 0.2 m deep and the measured values being no more than 1.0℃. The influence of the cold air infiltration, the heat source on the soil surface due to the solar radiation, and the soil temperatures at a depth of 1.0 m on interior temperatures were also discussed in this paper. The model can help to select suitable solar greenhouse design before the construction and to predict inner temperatures for different climatic conditions outside.