Abstract: As the proportion of new energy continues to increase,the coupling degree between the millisecond level transient control of power electronic equipment and the second level dynamic characteristics of the power grid is deepening. However,the current simulation system cannot meet the analysis requirements of complex large-scale power grid in terms of scale and speed. Therefore,a fast simulation system for grid with high proportion of new energy is proposed based on equivalent simplification and GPU. Based on the control model and connection impedance,the large-scale converter equipment is aggregated equivalent,and the simulation scale of multiple converters is simplified under the premise of ensuring accuracy. The grid structure is simplified in different regions,which is convenient for parallel computing and reduces the computational complexity. The simulation of the power grid is completed by GPU parallel computing,which improves the running speed of simulation system. Through the combination of aggregation equivalence,partition simplification and parallel computing,the rapid simulation of high proportion of new energy grid is realized while ensuring simulation accuracy,and the operating characteristics of grids with high-proportion new energy are accurately and quickly analyzed.Finally,the accuracy and operating efficiency of the proposed simulation system is verified through an example.