This paper proposed a real-time simulator for DC microgrids research. The simulator is implemented with different computation modules which simulate designated generation, storage, load of the microgrid. The back-bone of the microgrid is simulated as well using one computation module. To verify the proposition, a boost converter, dc load with periodic consumption and the transmission line structure is firstly simulated with real circuit element as well as C-code module. The distributed real-time simulation hardware platform is built using LAN router as the data exchange equipment, and the experimental results further verify the accuracy and feasibility of the distributed circuit model of DC microgrid. In the real-time digital environment, the fault control and propagation mechanism of DC microgrid are analyzed in detail, laying the foundation for the future research.