A 2N+1 level modulation method of modular multilevel converter (MMC) is studied in this paper.The N+1 level modulation is analyzed.The realization principle of 2N+1 level modulation method is deduced on the basis of fully understanding the working principle of MMC,and the specific implementation process is given according to the situation of odd and even.Simulation results show that comparing with the N+1 level modulation mode,2N+1 level modulation mode can achieve 2N+1 level output with more waveform levels and low harmonic content,but the cost is the increase of bridge arm circulation and inductance drop.The feasibility and validity of the 2N+1 level modulation method are verified.