This study investigates the endogenous relationship between abnormal insider trading and accrual abuse, and explores whether corporate governance affects this relationship. Our results suggest that insiders take advantage of private information on abnormal accruals to time their trading and manipulate accruals opportunistically to mislead the stock market prior to their planned trading. More important, we find that the abuse of inside information for stock trading becomes more serious when a firm's ultimate controller has a great divergence of control rights (or seat-control rights) from cash flow rights. We also find that higher family ownership and control, increased managerial ownership, or a dual leadership structure not only induces more private information trading prior to financial reports disclosure, but also intensifies accrual abuse for future trading. The results for composite governance indices are also consistent with our expectation. Taken together, our evidence suggests that a poor corporate governance system interacts with abnormal insider trading and abnormal accruals, thereby aggravating insider expropriation on outside investors.