Abstract: A new structure of the wall-climbing robot’s tracked sucker, which is different from the normal, is designed based on multi-body magnetic structure. According to the tracked sucker’s working condition and the magnetization character of the rare earth magnet， a mirror model is obtained about the working air gap between the tracked sucker and the wall surface, a formula for calculating the magnetization in the y direction is established, it is proved that the magnetic force and the magnetization of the new tracked sucker is much larger than that of the normal. In order to reveal the distribution rule of the magnetization in the air gap， the permanent magnet’s tip-effect is neglected, and a multi-harmonic formula is established, upon which the optimization principle of the design of the tracked sucker is presented. It fulfils the requirement of the wall-climbing robot moving safely on the wall surface.

Key words: Magnetization, Mirror model, Multi-body magnetic structure, Tracked sucker