The relations between tomato crops and soil transpiration and the microclimatic factors inside and outside bispan greenhouse were analyzed. The computational fluid dynamics (CFD) model was used to solve the temperature and relative humidity (RH) distributions based on water vapor transmission and solar radiation with the porous models, and the boundary conditions were discussed. The 3D temperature numerical simulations were tested by means of Fluent software. The results showed the average relative errors of the simulated and the measured values were 5.7% and2.1%, respectively. The CFD model and the boundary conditions were proved to be validated. Compared to cloudy days, the average temperature was 1.6℃ higher and relative humidity was 3% lower in sunny days. The solar radiation had an effect on the temperature and RH distributions. The average temperature was 0.8℃ higher and RH was 19% higher for the double density plants than that of single density plants. The temperature and RH distributions were lower near the leeward than the windward inside greenhouse, but a homogeneous pattern was observed in cropping region.