The topological circuit of the new DC transmission system based on the new converter transformer and its inductive filtering system is different from that of any existing high voltage DC transmission system（HVDC）. Based on the CIGRE HVDC first benchmark model， a new testing system is designed using the same parameters. The transient response characteristics of the conventional and the new system are simulated in detail with various typical disturbances that may occur in reality. The simulation show that the new system further increases the regulating margins of the HVDC transmitted power and retain satisfactory transient response characteristics. The system operates stably and adequately following various typical disturbances.