With further study of irrigation systems, more complete and complex optimization model of irrigation schedule have been proposed, and therefore advanced methods are required for solving the model optimization. This paper gave the steps of the simulated annealing algorithm to solve the model, and analyzed the characteristics s and effects of this algorithm in the process of solving the optimization model of irrigation schedule by case, and got the conclusions: the objective function value obtained by this algorithm was close to the global optimum. But the limitation of this algorithm was unstable objective value, which required repeatedly computing then to get the optimum. Therefore, the simulated annealing algorithm should be improved to solve the optimization model of irrigation schedule.