Abstract: A simulation training system for substation secondary circuits based on design drawing is presented. Automatic modeling technology is developed to convert the secondary circuit drawings in CAD format into dynamic drawings. The elements in the dynamic drawings are mapped to the devices in a 3D substation simulator, which make it possible to measure and operate the elements in secondary circuit through 3D substation simulator. At the same time, the changed state of element in 3D substation simulator will be displayed on the dynamic drawings simultaneously. A simple and practical algorithm was adopted to calculate the node voltage of secondary circuit rapidly and accurately, which can provide data for simulation and measurement of secondary circuit and action logic of elements. The system based on the secondary circuit drawing of 500kV Nanning substation has been put into use in Nanning Bureau of CSG EHV Company.