Competition in the product market is an excellent mechanism for the optimal allocation of resources and has disciplinary effects on managers' behavior and their inadequacies, as well as applicant effects on management incentives to manipulate profits and, in a way, reported earnings management. The purpose of this study is to investigate the relationship between differentiation strategy and earnings management: the moderating role of competition in the product market "in Tehran Stock Exchange. For this purpose, 130 companies have been selected as a statistical sample in the period 1392-1397. The method of the present study is multiple linear regression in terms of applied purpose and statistical method used. The results show that differentiation strategy has a negative relationship with earnings management. Another result of the research is that competition in the product market affects the relationship between differentiation strategy and profit management. Therefore, to achieve long-term success and sustainability of the company's performance, they benefit from different strategies to achieve the financial goals of using real profit management.