Abstract: The auto-vectorization of raster map is the important way of the collection of geographic information. But at present, the result of the main software for auto-vectorization is bad with some aspects which make the great computation of disposing the vector lines. It’s designed the Scan-thinning-algorithm based on the morphological characteristics of the raster lines. This algorithm though 3 steps to thinning the raster lines, first, tracking the undetermined pixel by pushing with the sequential of the line; the second, obtaining the Center-pixel by scanning truncation of the line; finally, connection the present Center-pixel and the last Center-pixel with the ordinary Thinning-pixel. The result of the Scan-thinning-algorithm has some characteristics, less influence of the edge conditions, less Center-pixels, and grate precision. It’s designed the auto-tracking-vectorization algorithm dispose the result of the Scan-thinning-algorithm. By the way, reduced the working of coordinate transfer, at the same time the result of this algorithm has some characteristics, less nodes, the smooth result approach with the center of line, do not mutual interrupted at the intersection, so that , which greatly improved the efficiency of auto-vectorization and post-processing. Finally, this paper introduces the auto-vectorization and the post-processing method of the raster area map.