The invention provides an electromagnetic transient simulation method and device for a permanent magnet direct drive wind turbine generator. The method comprises the following steps: acquiring operation parameters of a simulated permanent magnet direct-drive wind turbine generator and simulation parameters of a single-machine model; constructing a power amplification model; and performing electromagnetic transient simulation on the permanent magnet direct-drive wind turbine generator based on the power amplification model, wherein simulation parameters comprise main circuit parameters, direct-current bus current parameters and control parameters. According to the method, large-scale simulation of the permanent magnet direct-drive wind turbine generator can be achieved, occupied resources in the simulation process are small, and the simulation precision is high. According to the invention, the established power amplification model is active in steady state and transient state. The reactive characteristic and the steady state and transient state active power of the single-machine model are realized. The permanent magnet direct-drive wind turbine generator is simple in structure and consistent in reactive characteristics, the power of a single permanent magnet direct-drive wind turbine generator can be amplified by N times through the power amplification model, thousands of MW oreven larger-scale wind power plant simulation models can be built with few power amplification models, and the requirements of large-scale wind power plant transient analysis tests are met.