A process-based corn simulation model (MaizeSim) was coupled with a two-dimensional soil simulator (2DSOIL) to simulate the transpiration and photosynthesis of corn under drought stress. To simulate stomatal reaction to draught stress, two stomatal controlling algorithms (control by hydraulic signal and control by non-hydraulic signal) were implemented in MaizeSim. Corn plants were grown in sunlit growth chamber and irrigated with different amounts of water. Simulated transpiration and photosynthesis rates were compared with those measured from the chambers. Comparison results indicated that the coupled model was able to simulate the changes in transpiration and photosynthesis rate of corn plants under drought stress, and that a model with stomatal controlling mechanism performed better than one without stomatal control in simulating transpiration of corn plants on drying soil. When simulating corn transpiration under drought stress, the algorithm with with hydraulic signal performed better than the algorithm with non-hydraulic signal. Reasons for these differences were discussed. It was also found that the simulated photosynthesis rate was not as sensitive to stomatal closure as the simulated transpiration. The result agreed with the differences in sensitivity of photosynthesis and transpiration to changes in stomatal closure that have been reported in the literatures. These results suggested that the coupled model not only is a valuable tool in studying corn transpiration and photosynthesis under drought stress, but it also provides a platform to implement and evaluate algorithms in studies on corn crop water dynamics and CO2 assimilation.