In order to solve the problem that the large-scale security and stability control system can not be tested in the laboratory, a data conversion device is designed to interface with the on-site operation stability control device, which realizes the information exchange between the RTDS test system of the simulation laboratory and the remote operation equipment. The overall design of the data interface conversion device is introduced in detail, and combined with the typical application of the device.The application method and practical application of the data conversion device in the wide area remote testing system based on RTDS are further elaborated, extends the test system to the on-site operation equipment.The laboratory′s present situation is realized,and the closed loop test of field security and stability control system is completed. The design of the device and the application of remote test method provide the experimental basis for the remote simulation test of the the large-scale security and stability control system.