To solve the problem of numerical oscillation in electromagnetic transient calculation and improve the computational efficiency of electromagnetic transient simulation, this paper proposes a new electromagnetic transient parallel computing method, which uses 2-stage 3-order Radau ⅡA method to discrete continuously at multiple time points, and then solve the problem by applying Newton method. Since the 2-stage 3-order Radau ⅡA method has good calculation accuracy and stability, the proposed method can not only perform parallel calculations at a larger step, but also eliminate numerical oscillation. Case calculations prove that this method not only eliminates the numerical oscillation, but also effectively improves the accuracy, efficiency and real-time performance of the electromagnetic transient simulation of the power system.