Abstract: Collision detection of urban underground pipelines is very significant for pipeline design, pipeline detection and urban safety. Aiming at the problems of low accuracy, inefficiency and dependence on existing commercial platforms in current collision detection algorithms for urban underground pipelines, an efficient and precise collision detection algorithm for underground pipelines is proposed, which is based on projection along common perpendicular. The algorithm classifies the three-dimensional spatial relationship between two pipe segments into two categories including coplanar and heterogeneous. When the central lines of two pipe segments are parallel, collinear or intersectant, whether they collide with each other can be easily judged through the geometric relationship of their center lines and radius size; if the central lines of pipe segments are in different planes, the projection transformation is carried out along the direction of the common perpendicular line first to reduce the spatial dimension, and then the minimum surface clearance between them is obtained through computing the maximum distance between circle and ellipse. Based on the computation above, our proposed algorithm can easily realize precise collision detection for pipelines. Experimental results show that the algorithm not only has high collision detection accuracy for three-dimensional spatial pipelines, but also has good computational efficiency.