A modified analytical model of the NC-tool path for face milling of flat convex surfaces is developed. The staircase milling for the path parallel to the specified edges of a polygon is considered. Differing from the former approach, the influence of the location of the starting point, the supplement of a path for the uncuts parts, and the end reduction are permeated in this paper. Using the modified model, the object can be machined completely and the total length of tool path will be reduced.