Water state of plants has an important effect on their growth. In this paper, water state of plant leaves were simulated using Fluent, a CFD simulation software, and principles of physiological structure of plant leaf and the water transportation were analyzed through combination of plant physiology and fluid dynamics. Firstly, a simulation model of plant leaves was established in Gambit, a preprocessor software for Fluent; after that, the model was simulated in Fluent; then the results were exported to Tecplot, a post-processing software; finally, three-dimensional data graphics of the distribution of velocity, temperature and pressure were obtained, and analysis on the simulation results were made. The result of this paper is helpful for the further study of plant leaf physiology and future water-saving irrigation.