Based on the development， establishment and tests of the digital-analogical hybrid HVDC simulation system of the Simulation Center of China Electric Power Research Institute， a discussion is made on the design principles， technical measures， simplification and optimization methods that help the digital-analogical hybrid HVDC simulation system to become more practical， efficient and suitable for simulation tests. Focus is on several kinds of equipment configuration; the optimization of primary and secondary physical parts; the adjustment and modification of system hardware and software; and the elaborate design of those interfaces between different devices. By means of appropriate interfaces and communication， the primary and secondary physical parts are interconnected. The interconnection is realized with other DC and AC simulation systems and with the auto-control devices. Moreover， the simulation system can be controlled and monitored by the data acquisition system and workstation.