In order to realize grid connection and transient real-time simulation of DFIG, a multi-rate parallel real-time simulation method based on co-simulation of Field Programmable Gate Array (FPGA) and CPU is studied. The switching function method is used to model the “back-to-back” converters in the DFIG and optimize the resources, and the modeling segmentation between systems with different step is completed based on PWM averaging to realize multi-rate parallel simulation. The small-step simulation of the “back-to-back” converter is realized with an operational step of 200 by use of high operational rate and strong parallelism of FGPA. Facing the needs of real-time simulation of active distribution network, the 200ns/50 parallel co-simulation of FPGA and independent parallel real-time simulator UREP is realized. By comparing with the off-line simulation results of Simulink and analyzing FGPA resource consumption rate before and after model optimization in this paper, the real-time capacity and accuracy of research method in the paper are verified, which provide a reliable technical support for grid connection and transient research of all kinds of wind power systems.