Abstract: Business Judgment Rule started from prosperity of theory of freedom and laissez-faire in the American society in the 19th century. Business Judgment Rule emphasizes corporate management should do everything good for shareholders. But meanwhile, it also admits the management of corporate could escape the scold from shareholders under this rule. It looks contradictory. As a matter of fact, the nature of Business Judgment Rule is an expression of court restriction, which respects the board and prevents the unreasonable interference of court.