To improve construction management in the urban rail-transit, the WBS concept is well exploited by crossing a horizontal breakdown of urban rail-transit construction activities with a vertical breakdown of its technology system, thus a WBS matrix is obtained, which is more complete and useful than the WBS tree. This article firstly stated the concepts of interface and WBS matrix, with urban rail-transit analysis of how to use WBS matrix to improve interface management. The composition, structure system and principle of WBS matrix were specifically analyzed by contrastive method. The handling efficiency of WBS concept was decided by the changing of the factors.