Several mathematic methods used in the numerical control system of profile followed grinding robot are described. Cubic parametric Spline surface function is employed to fit the geometric model of the surface grinded with high precision. Improvement of the physics performance of blade is obtained by reconstructing the large size surface of turbine blade based on calculation geometry. Graphic linear transfer technique is provided to users with unique format of programming. Graphic non linear transfer technique is used to solve some more difficult problems successfully including transformation of the coordinates of comtrolled points in multicoordinates system, adjustment of the attitude of grinding head as well as realization of constant pressure grinding. All these mathematics methods are demonstrated feasible and efficient in actual practice and are valuable in developing large size surface grinding robots.