An investigation is made on the harmonic distribution characteristics of the HVDC transmission system useful for analyzing the harmonic distribution in electric devices and electric system as well as the effect of harmonics on the electric devices. A new HVDC circuit topology using the new converter transformer and inductive filtering technology is described. The mathematical models for calculating the harmonic characteristics are developed for both the inductive and passive filtering technology and their effects of the HVDC harmonic characteristics are analyzed. It is shown that inductive filtering is capable of suppressing the harmonic at the valve side， thus avoiding the harm of the harmonic on the converter transformer brought about by traditional filtering. The correctness of the analysis is verified by test results.