Abstract: In order to improve the power capture efficiency of wave energy converter (WEC) while satisfying various constraints of the system during operation, this paper proposes a variable coefficient model predictive control (MPC) strategy for direct-drive wave power generation system considering field weakening effects, with the objective of maximizing the average capture power. As for the problem of over modulation of converter output voltage caused by excessive wave excitation force, this paper introduces field weakening control into optimization algorithm to increase the operating range of system and improve the power capture efficiency of WEC under demagnetization-limit of generator. In addition, based on simulation analysis, the corresponding relationship between the regularization coefficient in the MPC objective function and the average capture power is found via simulation tests. On this basis, fast Fourier transformation (FFT) and superposition theorem is employed to establish a variable coefficient MPC control strategy for direct-drive WEC available for irregular wave input. The simulation results show that the proposed scheme can effectively improve energy capture efficiency while meeting system constraints in irregular waves.