Abstract: In order to carry out experimental verification on the protection and fault clearance strategy based on DC grid, we develop a four-terminal DC grid physical platform according to the network structure of Zhangbei DC grid. The pseudo-bipolar connection at DC-side is adopted in the platform, and each bridge arm is cascaded through a full-bridge modular multiple converter (MMC) sub-module. In terms of controller structure, the physical platform includes 3-level control structures, such as upper computer, crate controller, and sub-module crate, communicating through the Ethernet and optical fiber, respectively. And all control algorithm is set in FPGA of crate controller, realizing packet sequencing voltage-sharing strategy of the capacitor of sub-modules (SMs) to simplify the control method and improve response speed of controller. The good performance of physical platform is verified by the experiments of normal operation and power step change. Finally, the experiment of fault clearing is carried out.The results show that the physical platform has the hardware ability to carry out the research of DC power grid protection and fault clearing, which can provide good hardware support for the follow-up research.