Offshore floating photovoltaic (OFPV) systems experience motion and shading under wave action, requiring optimization of system layout and structural design to maximize solar radiation capture and reduce shading losses, thereby improving power generation performance. Focusing on block-type floating bodies, block-type floating bodies were first analyzed for their dynamic response characteristics in a wave environment, and the boundary conditions of floater motion were clarified. A power generation model under dynamic tilt angles was established by combining the tilt-angle variations induced by wave motion with an irradiance calculation model for inclined surfaces. Subsequently, a dynamic shading model under wave action was developed to quantify the effects of waves and module layout on the power output of the FPV field, based on which an optimization design method for offshore floating photovoltaic performance that accounted for wave influence was proposed. Finally, hydrological data from a specific sea area were used to conduct simulations. The results show that the energy yield of the optimized system is increased by 13%~16% compared with the non-optimized scheme, thereby verifying the effectiveness of the proposed optimization method.