A relay protection dynamic testing system based on new type real-time digital simulation is presented. The system uses RT-Linux and high performance industrial control computer to compute, applies the Matlab/Simulink to develop the model file, adopts PCI interface card to I/O, employs special switch grouping technology to output peer-to-peer data, and uses flexible configuration program to achieve auto-test. It also can solve many problems, such as the calculation time jitter, simulation numerical oscillation, multi bays synchronous output and so on. The system is suitable for real-time dynamic simulation test of conventional protection, intelligent protection and station domain protection.