Turbine blade root are commonly processed by grinding, and the grinding process parameters determine the surface quality and fatigue performance. The paper investigated the effect and mechanism of grinding parameters on the surface roughness and hardness of third generation nickel-based single crystal superalloy DD9 based on orthogonal experiment. The experimental results show that grinding surface roughness were mostly affected by the wheel speed vs, followed by the workpiece feed vw, the grinding depth ap had few effects on the grinding surface roughness. The machining hardening appeared at the grinding surface for grinding DD9, the hardening degree were ranged from 1.9% to 13.8%, and the depths of hardening layer were between 60 and 120μm. In order to obtain the small surface roughness, uniform texture and small degree of hardening in grinding DD9 super-alloy, a grinding parameter scope was recommended as, vs ? [20m/s，25m/s], vw ? [12m/min，16m/mim], ap ? [10μm，15μm]. The conclusions provide theoretical foundation for grinding third generation single crystal turbine blade tenon toothe.