With the increasing density of maritime traffic, offshore wind turbines face the risk of collisions with vessels. To enhance the collision resistance performance of offshore wind turbines and maintain their safe and stable operation, as well as extend their service life, a novel biomimetic fractal-based protective device inspired by the lotus leaf vein structure is proposed for offshore wind turbines. Using LS-DYNA, a nonlinear finite element model is employed to simulate the collision process between the offshore wind turbine foundation and a vessel traveling at 2 m/s. The protective performance of the biomimetic fractal protective device is analyzed and compared with a conventional traditional protective device, including the system contact force, tower stress, stress in the high-stress zone of the column and foundation connection, and energy conversion. The simulation results show that compared to conventional protective devices, the biomimetic leaf vein structure can reduce the maximum contact force applied to the wind turbine, resulting in a smaller high-stress region in the contact area and a significant overall reduction in stress. Additionally, the biomimetic leaf vein structure enhances the protective capabilities of the device at the connection between the column and the foundation, reducing the maximum stress at the connection and significantly lowering the average stress. Compared to ordinary protective devices, the main protective material of the biomimetic fractal structure absorbs more kinetic energy while experiencing a smaller increase in internal energy, leading to greater energy dissipation and significantly improved energy absorption efficiency of the steel shell. Overall, the biomimetic fractal structure protective device demonstrates superior comprehensive collision resistance performance compared to traditional conventional protective devices.