Modern enterprises survive in the fierce market competition and generally face the problem of capital shortage in the process of development. With the continuous development of enterprise capital structure theory, debt management has become the choice of more enterprises. I. The meaning of capital structure and debt management Capital structure and debt management are a pair of closely related but different concepts. Capital structure belongs to the category of static concept, which theoretically reflects the proportional relationship between debt funds and equity funds of enterprises, that is, to clarify the proportion of debt in all funds of enterprises. Debt management needs to be understood from a dynamic perspective, emphasizing the application of capital structure in the production process of enterprises. When capital structure is used to earn profits, it is endowed with the connotation of debt management, that is, under the guidance of capital structure theory, enterprises make up for the shortage of their own funds by borrowing funds to engage in production and business activities, in order to obtain the maximum income and maximize the value of enterprises. Second, the capital structure theory is the basis of debt management (1) MM theory. The theory holds that in the absence of income tax, the value of any enterprise, whether it has liabilities or not, is equal to the operating profit divided by the rate of return applicable to its risk level. The value of enterprises with the same risk is not affected by the presence or absence of liabilities; In the case of income tax, there is tax avoidance interest, and the more liabilities, the greater the value of the enterprise. (2) Trade-off theory. According to this theory, MM theory ignores two factors in modern society: financial distress cost and agency cost.