In order to find out the change law of the physical properties of the pantograph-catenary arc under lightning overvoltage, the physical analysis model of the pantograph-catenary arc under lightning environment is established based on the fluid dynamics theory and the COMSOL finite element simulation software. The arc characteristics under different overvoltage conditions are simulated and studied, and the change and development rules of the arc are obtained. The results show that the arc voltage, arc diameter and current density of pantograph and catenary are changed due to the effect of lightning impulse voltage; As the arc voltage continues to increase, the arc current density first increases and then decreases.