Abstract: When the modular multilevel converter（MMC） is applied to the medium voltage DC distribution network, the number of sub-modules is small. Following the nearest level approximation modulation strategy in DC transmission system will cause such problems as severe current distortion, poor output voltage quality. To solve the problems, we analyzed the existing modulation strategy principle of MMC, and proposed a double multiplication hybrid modulation（DMHM） strategy suitable for medium voltage DC distribution network accordingly. This modulation strategy uses different rounding functions for the upper and lower bridge arm voltage reference waves and superimposes the PWM wave to expand the level output to 2N+1. In addition, DMHM determines the operating mode of sub-module according to the capacitor voltage sorting result. At any time, only one sub-module per phase works in PWM mode, which can effectively equalize the capacitor voltage and make the control simpler. Finally, the MATLAB/Simulink simulation verified the effectiveness of DMHM in medium voltage DC distribution network. Compared with the traditional modulation strategy, DMHM can reduce the harmonic content, and the switching loss and switching frequency are much smaller than that under CPS-PWM modulation.