To address the impact of large-scale offshore photovoltaic pile groups on nearshore wave fields, a generalized model method adopted SWAN model based on equivalent bottom friction coefficient was proposed to solve the bottleneck of low computational efficiency in full-grid simulation of high-density pile foundations. Based on the method, the attenuation effect of 50 000 pile foundations on wave fields under different working conditions in the offshore photovoltaic area of Qizi Bay, Qingdao, Shandong Province was simulated. The results indicate that the pile group has a significant blocking effect on wave propagation; the wave height attenuation gradually increases from sea to land, and the wave height attenuation rate on the nearshore side can reach 30% under extreme conditions. This method can effectively solve the computational difficulties in simulating large-scale pile groups and provides technical means for the wave field impact, pile foundation design, and parameter selection of offshore photovoltaic projects.