In order to study the influence of the HVDC project on the power grid, the concept of engineering image simulation is proposed for an HVDC control and protection system, and its implementation method is studied. First, the basic principle and key technology of engineering mirror simulation are analyzed, and then the engineering mirror simulation tool NewLinkC configuration software platform is developed for the typical development platform SIMADYN D of DC transmission control and protection system. The DC control protection simulation program function module is completed using NewLinkC and encapsulated into a DC control protection simulation module which can be identified by RTDS. It constitutes an RTDS closed-loop AC/DC real-time simulation system with an existing RTDS system component simulation module such as an AC system, converter transformer, converter valve, DC line, filter, etc. Finally, taking the Gui-Guang II HVDC transmission project as an example, the transient process of the actual control and protection system and the mirror system are compared and analyzed. The results show that the mirror system can accurately reflect the operational characteristics of the actual control and protection system, and can replace the actual control and protection system for the simulation research of DC transmission engineering. This work is supported by the National Natural Science Foundation of China (No. 52007143).