Optimize the capital structure of the substance is to seek the lowest weighted average cost of capital rate. Enterprises can lower the cost of capital by determining the condition of the existing capital structure, simulation and then by adjusting the proportion of shareholders' equity and debt, to re-calculate the weighted cost of capital rate after adjustment, combined with the financing capacity of the actual business of equity and debt, and the need to operate the total amount of capital, to select the appropriate capital structure, optimize the capital structure, so as to realize minimize the cost of capital.