Based on the empirical data of Chinese listed companies from 2007 to 2011, this paper investigates the effect of relationship-specific transaction on the managerial opportunism behavior. The empirical study indicates that relationship-specific transaction in terms of supplier and customer is negatively related to investment efficiency, which will increase overinvestment and underinvestment. The relationship-specific transaction will lead to rent, but at the same time brings about a series of negative effects. Further studies show that the negative relationship between relationship-specific transaction and investment efficiency will decline with the development of internal control. What's more, research shows that high quality internal control, as a credible commitment, can effectively suppress opportunism behavior, control and reduce risk, improve the information disclosure credibility, alleviate information asymmetry, thus inhibiting the underinvestment or overinvestment triggered by relationship specific transaction.