In traditional NC curve grinding, the grinding wheel’s rotary surface is generally not on the grinding point’s normal direction, which will bring the distortion of grinding wheel and decrease the machining precision. This paper presents a new technology, which is called the non-interference normal tracking for NC curve grinding process. By controlling the worktable to rotate in the x-y plane, the superposition between the rotary surface of the grinding wheel and the normal vector of the workpiece’s contour is realized, and the interference between the wheel’s body and the workpiece could be avoided at the same time. A mathematic model is established and an algorithm to calculate the worktable’s rotary angle is proposed. Finally, the algorithm is applied in a new-type digital curve grinder successfully. The results show that the method is reliable and effective.