Abstract: The influence of the change of livestock breed structure on the grassland degeneration is studied, and the motivating and restraining mechanism of grassland resource protection is set up. On the basis of some mathematics models, the influences of overload grazing with two breed livestock structure on the grassland degeneration and economic effect are analyzed, and the optimal unit punishing quantum for restraining farmers' taking overload grazing and urging them to adjust livestock breed structure is designed. Finally some principles of designing the incentive and restraining mechanism to optimize livestock breed structure and to protect the grassland resources are put forward. It can promote farmers to optimize livestock breed structure and change their behavior of overload grazing.