Abstract: To improve reliability and security of the oil tank inspection operation,a wall-climbing robot mechanism with variable magnetic adsorption device is proposed and its weld seam surmounting characteristic is studied.Firstly,The ANSYS platform is used to carry out simulation analysis on the variable magnetic adsorption device,and the magnetic flux density distribution and magnetic adsorption force of the robot body are gotten.Then,a dynamic model of the weld seam surmounting process is established.The ADAMS is used to carry out dynamics simulations,and the variation curve of magnetic adsorption force during the course is gotten.The reasonableness and practicality of the proposed structure are verified by analysis.