Abstract: With regard to the important part of extruded direction played in feature extraction of an extruded surface in reverse engineering, a method on extracting the extruded direction of extruded surface is presented. Firstly, the principal curvature and direction on each point is estimated based on unorganized point cloud. Then the minimum principal direction is utilized to obtain the initial extruded direction through a sequence of procedures, such as planar data filtering by Gaussian curvature and mean curvature, mean direction calculating about minimum principal direction based on the statistics of directional data, outlier data filtering based on deviation analysis, and so on. Secondly, in order to get a precise extruded direction, a refine algorithm of minimizing the projective area of the point cloud projected onto a plane perpendicular to the extruded direction is presented,and a pattern-searching algorithm to refine the extruded direction is applied. Experimental results illustrate the feasibility of the new algorithm.