According to Coase and Alchian's definition ,the corporation is a contract consisting of variety essential factors.The essential factors of the firm can be separated into human capital and non-human capical. The owner of the factors will be confronted with rearrangement of the property rights when forming a contract. At the same time, the firm is a special contract which different from other short-term contract. Therefore, its property rights arrangement is dynamic and its surplus distribution is dynamic ,too. By analyzing the arrangement process of the property rights and surplus, the paper draws a conclusion about distribution equilibrium.