Gallium Nitride (GaN), a leading third-generation semiconductor material, offers exceptional properties and broad application potential. However, its high hardness and chemical inertness make GaN wafers difficult to process, posing significant challenges in improving the polishing efficiency. During the electrochemical mechanical polishing (ECMP) process, the oxidation effect on the GaN surface critically affects the material removal rate (MRR). While various methods have been developed to enhance the concentration of hydroxyl radicals (OH*) to improve the process, their instability and rapid decomposition present further obstacles to maintaining concentration and stability. The present study proposed a novel approach using sodium tripolyphosphate (STPP) as an electrolyte additive for ECMP under a green Fenton reaction. Furthermore, the MRR and surface roughness (