The utility model provides a digifax hybrid simulation of HVDC system platform based on ADPSS, including simulation platform, signal interface device, HVDC control and protection system and the online monitored control system of HVDC, one time simulation platform is connected with HVDC control and protection system through the signal interface device, and HVDC control and protection system passes through the net twine and is connected with the online monitored control system of HVDC, a simulation platform includes electromechanical model of AC electric network and HVDC system electromagnetism model, be electromechanical model of AC electric network and HVDC system electromagnetism model through electromechanical the electromagnetism interface is connected. The utility model discloses can simulate the relation of connection between AC electric network and the direct current system effectively, effectively the interaction between the simulation and analysis alternating current -direct current series -parallel connection electric wire netting to and the influence of interaction to protecting between the friendship DC electric network.