The invention relates to a simulation method and a device for large-scale distributed generation. The method includes decoupling a distributed generation simulation system into a physical simulation system and a control information simulation system. Physical simulation system and control information simulation system are simulated by independent CPU. The technical proposal provided by the invention reduces the numerical oscillation caused by the time delay generated by the communication between the decoupled physical simulation system and the control information simulation system, fully exerts the performance of the parallel calculation of the CPU, accelerates the simulation speed, and provides technical support for the large-scale active distribution network simulation.