This paper constructs the evaluation index system of general managerial discretion for branch companies in large statowned enterprises from the following three perspectives: general managerial discretion of investment decision, product sales and human resource management. It also does the evaluation and empirical study based on the data of questionnaire investigation. The result shows that the general managerial discretion of human resource management has reached better level for branch companies in large stateowned enterprises, on the contrast, the general managerial discretion of investment decision is relatively poor; general managerial discretion of branch companies have positive effects on branch companies’ performance. However, the positive effects will weaken after the general managerial discretion reaches a certain point. At the same time, general managerial discretion of investment decision in branch companies has the most obvious effect on branch companies’ performance. Finally, it puts forward certain concrete countermeasures to strengthen general managerial discretion according to the problems finding. Besides, this research also indicates that, because branch companies have obvious characters that they are “legal person” and there are agent problems between general corporations and branch companies, the way by which general corporation treats branch companies should realize the transformation from traditional management to governance. Nevertheless, it will lead to such theoretical puzzles as “necessity of governance of branch companies”.