In view of the existing low efficiency of method problems about the optimization of water allocation of canal system, a multi-objective model about optimization water allocation was established to acquire the highest increased yield benefit and water income of the irrigation district under the basic of soil moisture and the water production function. The information of land use and soil moisture in irrigation area was gained easily by RS technology. The optimization water allocation in each branch under the condition of multi-objective could be obtained by the model solution with ant colony algorithm in GIS system of each the image pixeles. The result accorded with the practical situation of water use in irrigation area. Therefore, this model can be widely used for decision makers to optimize water resources distribution. 