Abstract: Detailed comparison is a methodology in the process of perfecting legal systems. Applying the method to the comparative study of shareholders' agreement system can comprehensively reveal the functions of shareholders' agreements. In terms of closely held corporation， China and the United States share a common legislative purpose， both of which allow flexibility in the management of such companies based on efficiency and cost. However， shareholders' agreements have a different status in the corporate law system of the two countries. Shareholders' agreement in Chinese corporate laws is an exception to the resolution mechanism of shareholders' meetings， but an exception to the board centrism in the United States. The content and procedures of shareholders' agreements in American laws are relatively clear， while the outcome of shareholders' agreements in Chinese laws is uncertainty. The historical evolution of shareholders' adjustment to power distribution through shareholders' agreements in American corporate laws reflects the deepening of laws' understanding of corporate governance mechanisms and the nature of corporate law norms. Accordingly， China should set clear rules about shareholders' agreements while revising corporate laws.

Key words: detailed comparison; shareholders' agreement; power distribution; corporate governance mechanism