Recently, scholars and practitioners have focused on the inverse relationship between managerial payment and corporate performance, which shows how the principle-agent theory cannot adequately explain the decision mechanism of managerial payment. Based on the Managerial Power Approach, the book brings managerial discretion into the investigation on managerial pay. The book makes contributions such as: it constructs measurement index system of managerial discretion based on public reports. The classical ERIC questionnaire measures managerial discretion directly from CEO's by 63 items, while the book divides managerial discretion into resource co-operation power, structure-position power and expertise-reputation power, and then measures them by public report. The two methods have the similar results, and this method has the advantage of being low cost, and easily carried out. It confirms that managerial discretion can manipulate the managerial pay level by the regression analysis of managerial discretion and managerial pay level. It also confirms that the pay level goes beyond the reasonable level too much with the accretion of managerial discretion, which shows that the manipulation effect on pay level does exist. then the book describes the manipulation effect quantitatively. By curve estimation of monitoring intensity effect on manipulation effect, it also gives other relationship curves between them, which shows that the manipulation effect decreases significantly with the accretion of managerial discretion. The book constructs pay performance sensitivity model based managerial discretion. Based on Saltuk Model, the book brings managerial discretion and proves that managerial discretion and pay-performance sensitivity are negatively associated. Then the book confirms that pay performance sensitivity will decrease with an increase of managerial discretion by regressional analysis.