A wallclimbing robot can be used for the rust removal task of fishing vessels. And the robot is inevitably required to surmount weld seam when operating on the hull plate. For the wallclimbing robot with inflatable wheels and suspended magnet, the compression of the tires is decreased after surmounting weld seam, which leads to an increase in the air gap between the magnet and the hull plate with a following decrease in the magnetic adsorption force. Thus the load capacity of wallclimbing robot is weakened, which affects the reliability of wallwalking. In order to solve the problems mentioned above, a research on the dynamic process of the wallclimbing robot surmounting weld seam was carried out. Firstly, based on the drivewheel tires simplified as spring dampers, a dynamics model of the wallclimbing robot surmounting weld seam was established, and the weldseam surmounting process of the drivewheel was divided into different stages. Secondly, a numerical method was proposed to solve the dynamics model. Meanwhile, the motion state of the wallclimbing robot with different values of tire pressure when surmounting weld seam was analyzed. Finally, experiment was carried out and the experimantal results were basically consistent with the numerical simulation ones, which verified the rationality and correctness of the established dynamics model. 