Abstract: This study aimed to investigate the influence of non-metallic inclusions on stress distribution in wind turbine gears, providing a theoretical basis for improving service life and reliability. It focused on the mechanisms by which inclusion morphology and size affect local stress concentration in the base material. Finite element software was used to establish and simulate 3D models containing inclusions of various shapes and sizes under different external loads. The results show that larger inclusions cause more significant stress concentrations. The study concludes that non-metallic inclusions are a key internal factor in early gear failure, and their stress concentration effects are strongly related to their geometry and material properties. Therefore, optimizing metallurgical processes and controlling the size and distribution of inclusions are crucial strategies for enhancing the material performance and extending their service life of wind turbine gears.