In the process of selective laser melting of metal powder layer-by-layer, frequent scanning is carried out by the scanning system，so reasonable selection of the laser scanning path is the main problem of this technique. A scanning path generating algorithm, called “blanking” was proposed in this paper. The implementation process of the algorithm is as follows: First, the scanning lines of each contour are generated, while the contour's shape can be divided into convex polygon and concave polygon, and the generating process of the scanning lines of each contour needs special treatments . In order to decrease the number of repeat calculation, the contours can be divided into a series of simply connected region. Blanking method will be used for the contour's scanning lines to generate scanning lines of the layer by the unit of simply connected region. Afterwards, the output order of the scanning lines in the simply connected region will be optimized by the rule of adjacent, and then the blocked final scanning lines can be obtained. These final scanning lines can be used for rapid prototyping process. Test result indicates that the algorithm has a high versatility, rapid generation of the scanning lines.