It is important to solve the problem of metal particle pollution inside the DC GIL. Using numerical simulation to calculate the trajectory of metal particles is an important method of designing particle traps and drive electrodes. In this paper, a 3D simulation method of dynamic particle motion randomly based on quadratic Rodrigues’ rotation is proposed to solve the trajectory of metal particles inside the DC GIL, considering the random reflection. Based on this model, the influence characteristics of random reflection angle, gravity inclination, particle size and other factors on particle motion are analyzed. From the results, the trapping efficiency of particle traps becomes weaker under the effect of gravity, and particles with larger sizes are more likely to escape. The drive electrodes set at the high voltage conductor can prevent particles from crossing the drive electrode. It can effectively improve the capture efficiency of the particle trap and increase the capture-escape ratio more than 45.9%.