Aiming at the multi-terminal flexible DC power distribution system which is based on DC bus with Modularized Multilevel Converter (MMC), this paper establishes the mathematical model of the 3-terminal MMC system connected with low voltage device and improves the coordinate control scheme based on the droop control method, referred to practical project. To avoid the usage of converter transformer, this paper designs zero sequence current restrain control loop. The case study is carried out on a simulation system built in PSCAD/EMTDC. The time domain simulation results prove the validity of the proposed control scheme. The active and reactive power can be reallocated stably by the proposed coordinate control scheme and the DC voltage suffers less fluctuation when system exception happens; the zero sequence current can be eliminated by the proposed zero sequence current restrain control loop, which is good for reducing over current and protecting the converter. This work is supported by Sino-US international Science and Technology Cooperation Project (No. 2016YFE0105300).