Abstract: In order to solve the problems of tedious manual operation and low design efficiency in the process of railway line design, this paper put forward the overall process of railway line horizontal vertical and cross real time linkage design, and studied the secondary development key technologies of digital ground model, plane interactive route selection, automatic design of horizontal vertical and cross-section and real-time linkage editing optimization based on AutoCAD platform and ObjectARX2010 development package, implemented many design functions, such as horizontal and vertical multi view design, automatic design of profile slope and slope constraint processing, automatic setting of vertical control points of profile, multi-grip point driving editing of horizontal and vertical entities, synchronous display of horizontal and vertical multi view by mileage, etc.The application example shows that this method can simplify the operation process, improve the efficiency of line scheme design and optimization, and provide auxiliary support for further improving the automation and intelligence level of line selection design.