With the wide application of modular multilevel converter (MMC) power electronic devices and the rapid development of AC&DC hybrid power grid, the higher demand is required for the power system simulation technology. A multi-time scale hybrid real-time simulation system for AC & DC large-scale power grid is presented, which is based on the “FPGA+RTDS+PC(parallel computer)” heterogeneous platform and is able to carry out hybrid simulation of fast electromagnetic transient, electromagnetic transient and electromechanical transient. The simulation system is composed of several simulation sub-systems such as VSC device, HVDC system and AC power system. Connected together by closed-loop interfaces, the system can implement multi-mode united calculation in multi-time scale and multi-grain parallelism. The system can also be interfaced with the EMS (energy manage system) as well as the dispatch control and characteristics display platform. Thus an accurate and efficient simulation tool for the test and study on complex AC&DC large-scale power grid is provided.