To accelerate the simulation rate of large wind farms, a model segmentation scheme based on equivalent short line decoupling is proposed. First, for a large wind farm with a single unit type, the method of output multiplication and collector line equivalent is used to simplify the modeling. In view of the shortcomings of short lines in wind farms, it is difficult to use the natural decoupling of long transmission lines to operate in parallel. Thus parameter compensation is proposed between the unit connection line after equal value and the long collection line connected to the booster station, so as to meet the decoupling criterion of the transmission line in one step. A simulation model is built in Matlab/Simulink, the model before and after segmentation is compared, and the simulation results verify the feasibility of the proposed scheme. On this basis, the state space node (SSN) method is used to divide the wind turbine into internal groups, and finally real-time simulation of large-scale offshore wind farms is realized on the RT-LAB platform.