Abstract: In this paper we present an automatic abstraction algorithm for building images.Firstly, the bilateral filter technique is used to remove the redundant details of the building image;and then the fast line segment detector with a false detection control is used to detect the outlines of the door, window or other edge features.Based on the line segments detected, a line-drawing image is generated by Flow-Based Difference-of-Gaussians filter to keep building's sketchy and clear outline features;at last the image from bilateral filtering and the line-drawing image are integrated to form the final abstraction result.With the presented algorithm, the redundant information is removed to abstract the detail content of the image, while a novel line enhanced technique is used to strengthen the special style of the building, which is similar to artist's hand-painting.Our algorithm is simple and easy to implement.And the experimental results verified the effectiveness of the algorithm.