Abstract: Aiming at the high complexity of the current layout plan of signal equipment in metro depot and the low efficiency of manual drawing with general AutoCAD, this paper constructed an auxiliary platform for drawing with user-defined entities as the unit. To solve the problem that the auxiliary platform can not share station data and interlocking data independently, the paper designed a specific data processing algorithm and external interface for it, used ObjectARX to create custom entities for secondary development of AutoCAD, designed human-computer interaction interface and external file input processing algorithm to implement human-computer interaction aided drawing and automatic drawing of layout plan of signal equipment, extended data output processing algorithm to complete the extraction of user-defined entity data, generated station yard and interlocking data, and outputted them to Excel through commands to implement the connection between data and interlocking software. The design results of the signal layout plan of a certain depot show that the platform can quickly generate the signal layout plan of this complex depot with one key in 2 seconds, and the drawing is accurate, which improves the design quality and efficiency of the signal layout plan of the depot.