Abstract: Transformer plays an important role in UHV transmission system. The overvoltage caused by arc faults in oil tank makes it possible for transformer to arouse explosion accident, which seriously threatens the safety and stability of the power grid. To explore the effect and law of arc characteristics on pressure generation caused by large current arc fault, the arc fault simulation tests were carried out under the conditions of different models of oil tank, currents, and electrode gaps, and the tests were based on the full-scale arc fault simulation test platform on AC turret of transformers, which is first domestically developed. During the tests, the pressure data on AC turret are collected, and the time-domain curve of pressure on the AC turret under different electrode gaps and different currents and the numerical relationship between the peak pressure inside the turret and the arc discharge power are presented. The study provides experimental and theoretical basis for the design of elevated seats for explosion prevention, promoting the development of transformer explosion prevention design technology.