The constant erosion of ocean waves seriously affects the safe operation and service performance of ocean engineering equipment， and ocean wave energy is a green renewable energy with many advantages. How to reduce the wave load and utilize the ocean wave energy through the hybrid wave attenuation and energy harvesting structure is one of basic scientific problems in the field of ocean engineering. The traditional wave attenuation and energy harvesting structure， especially the floating structures in the deep sea， has the technical bottleneck of wave attenuation and energy harvesting at a low frequency range. In this paper， based on the idea of reducing the equivalent dynamic stiffness of the system， a nonlinear hybrid wave attenuation and energy harvesting struc? ture is proposed， and the characteristics are studied. A new type of negative stiffness mechanism is designed and applied to hybrid wave attenuation and energy harvesting structure. In order to solve the fluid-structure interaction problem of nonlinear hybrid wave attenuation and energy harvesting structure， a semi?analytical nonlinear frequency domain method of hybrid eigenfunction expan? sion matching method and multi-harmonic balance method is proposed. The influence of the key parameters of the mechanism on the wave attenuation and energy harvesting performance is studied， and the “phase control” mechanism of the negative stiffness mechanism to improve the low frequency wave attenuation and energy harvesting performance is revealed.