Abstract: How executive tenure affects corporate earnings management is a central question in the field of corporate governance that urgently needs clarification. Based on data from non-financial A-share listed companies in Shanghai and Shenzhen between 2015 and 2024, this study empirically examines the relationship between executive tenure and real earnings management, along with its economic consequences, from the perspective of the dynamic game between "managerial motivation" and "power constraints". The results reveal a significant U-shaped nonlinear relationship between them. This U-shaped pattern is more pronounced in underperforming non-state-owned enterprises and firms with lower management shareholding ratios. Furthermore, CEO duality significantly strengthens this relationship. Further analysis indicates that accrual-based earnings management primarily exerts a negative impact on short-term corporate performance, whereas the adverse effects of real earnings management manifest more prominently in long-term performance. The findings of this paper provide empirical evidence for enterprises to curb earnings management and enhance earnings quality by optimizing executive tenure mechanisms and improving corporate governance structures.