In this paper, we propose an economic model predictive control (EMPC) strategy for the constrained optimization problem of the wave energy converter system. Unlike standard model predictive control (MPC) that uses the tracking cost function, in EMPC, a general economic cost function that directly reflects the economic objective of the system is established. In the wave energy converter (WEC), the general economic cost function aims to maximize the energy extracted from ocean waves and minimize the operation cost. The terminal equality constraint in the optimization problem is used to steer the system state to the steady-state at the end of the optimization horizon. Then the controller solves the non-convex optimization problem in real-time. The auxiliary optimization problem is used for the stability analysis, and the convergence of the system can be proved via the Lyapunov technique. Several simulation results are presented to demonstrate the effectiveness of the proposed strategy.