Abstract: The super control of major shareholders and insider control coexist in listed companies in China, and the agency cost and the "plunder" of major shareholders are combined into one. The irrationality of the shareholding structure is the direct cause of the super control of major shareholders and the control of insiders, and it is also the deep-seated reason for the weakening of the corporate governance mechanism. Therefore, the optimization of the equity structure is the key to improving the corporate governance structure, and the core of corporate governance should be to curb the "plunder" of large shareholders and establish a protection mechanism for small and medium-sized shareholders.

Keyword: Corporate control; Agency costs; Governance structure