This paper investigates how information asymmetry and mutual fund ownership affect listed companies’ earnings management. We show that(1) reducing information asymmetry improves firms’ earnings management behavior;(2)relative to short-term mutual funds, long-term mutual funds promote earnings quality by adopting a monitoring role; and(3) by dividing firms into high/low information asymmetry groups, we find that the information environment significantly increases the effect of long-term mutual funds on firms’ earnings management. In this paper, we provide new evidence for the role that institutional investors play in a typical emerging capital market. Our results have clear policy implications: to increase earnings quality, it is essential to improve information transparency and develop long-term institutional investors. We show that (1) reducing information asymmetry improves businesses’ earnings management behavior; (2) relative to short-term mutual funds, long-term mutual funds promote earnings quality by adopting a monitoring role; and (3) by dividing firms into high / low information asymmetry groups, we find that the information environment accounts increases obviously the effect of long-term mutual funds on firms’ earnings management. In this paper, we provide new evidence for the role that institutional investors play in a typical emerging capital market. Our results have clear policy implications: to increase earnings quality, it is essential to improve information transparency and develop long-term institutional investors.