This paper introduces and deeply analyzes the hazards of short circuit current to on-load tap changer. Based on the 3-dimensional simulation method of on-load tap changer subjected to short circuit current we established before, an optimized simulation is proposed in this paper, which considers thermodynamic interaction and actual short circuit current input waveform. On-load tap changer is a significant equipment in the electrical power system. It works to adjust output voltage under load. The safety and stability of on-load tap changer largely determines the safety and stability of transformer and even system. Short circuit current is risky to cause serious thermal and mechanical damage. The simulation and experiment of short circuit current are essential for the design and production of on-load tap changer. Simulation and corresponding experiment results of two domestic on-load tap changers are presented to demonstrate the proposed method can evaluate short circuit withstand capacity. The optimized simulation is helpful for design and verification of on-load tap changer, which integrates more influencing factors and improves accuracy and practicability of the short circuit current simulation model of on-load tap changer.