This paper proposes a new approach to tool path generation in precision machining of parts with sculptured surface. It aims to develop an effective NURBS fitting algorithm suitable for machining sophisticated parts requiring smooth profile on sculptured surface. In order to generate NURBS tool path with fewer control points, a dual-loop fitting technique is proposed in this paper. A general sculptured surface model is used to test the effectiveness of this method. It is shown that the proposed algorithm proved to be robust and effective in generating precise NURBS tool path. This makes the proposed algorithm suitable to convert conventional CNC tool path to more precise NURBS tool path. This approach may be of potential to be widely implemented in the manufacturing industry.