In response to the shortcomings of the existing wall-climbing inspection robots, such as inflexible steering and inability to move in all directions, a fully directional wall-climbing inspection robot is designed for large metal facade structures such as wind turbine towers and tank walls. This robot is equipped with four drive wheel sets, each of which has the functions of walking and steering. Different combinations of wheel directions can achieve different movement directions or modes. The adsorption method of this robot is permanent magnet adsorption, and the permanent magnet used for adsorption also serves as the magnetizer of the detection module. The wall-climbing robot must ensure no slipping or overturning during movement. Through static calculation, the stability conditions for the wall-climbing inspection robot to move on the wall surface are obtained. Simulation calculations of magnetic adsorption forces under different lifting conditions are performed to ensure that the magnetic adsorption force can meet the stable movement of the robot on the wall surface. A magnetic flux leakage detection model is established using simulation software, and then the magnetizer structure is optimized and analyzed to select a reasonable magnet size that provides appropriate magnetization intensity with minimal volume and weight, determining the optimal structural size.