Ship painting and rust removal and other operations are in great demand, and the application of wall-climbing robots in this field has become a research hotspot. Tile-shaped magnetic adsorption unit is the core device of robot walking on the wall of vertical steel facade. To improve the magnetic force and reduce the sensitivity of the magnetic force to distance, a new magnetic circuit design with Halbach array magnetization was used for the tile-shaped magnetic adsorption unit. The mechanical properties of the tile-shaped magnetic adsorption unit were studied by numerical simulation and experimental methods. The results show that the magnetic mass ratio of Halbach array magnetic circuit is 2.87 times that of conventional paired magnetic circuit, and the attenuation rate of Halbach array magnetic circuit is 0.5 times that of conventional paired magnetic circuit; Halbach array tile-shaped magnetic adsorption unit optimizes the magnetic circuit, weakens the magnetic field loss between the opposite magnetic poles, and enhances the magnetic induction intensity on the surface of the magnetic unit.