Abstract: The Van Genuchten Equation (VGE) which is used to describe the feature of soil water movement is super-set and nonlinear. Using traditional method calculating the VGEs parameters often results with a high margin of error because of complication and artificial factors. Genetic Algorithms (GA) is a new outstanding evolutionary computation method for solving complex nonlinear model. Therefore, application of real coding that based Poly-Population Genetic Algorithm (PPGA) on the VGE's parameters optimization is proposed. The results show that PPGA is a high effective algorithm with many good properties such as fast computing speed, high efficiency, high precision, small artificial factors and so on. Consequently, PPGA is a new method for calculating Van Genuchten equation parameters.