Abstract—Modular Multilevel Converter (MMC) is composed by hundreds of sub-modules (SMs). Such a large scale power electronic switches and power nodes will become very difficult to solve in the process of real-time simulation of the electromagnetic transient. These switches will occupy a very large amount of calculation, in this case, still use a large step (microsecond) simulation has been unable to meet the sub-module operation during dynamic  response, especially when a short circuit fault occurs in the bridge arm, the electromagnetic transient process of the system cannot be accurately reflected. In order to solve the problem, this paper presents a simplified sub-module model and an equivalent valve model based on state-space node solver implemented in FPGA for the real-time simulation. This method can effectively reduce the power nodes and decrease the computation time, and improves the accuracy of the simulation. In addition, the multi-rate simulation of RT-LAB and the test method of hardware-in-the-loop (HIL) are explained in this paper. Finally the simulation results show that the effectiveness of the proposed method.