The rapid development of science and technology and the application requirements of wall-climbing robots have made wall-climbing robots attract widespread attention. Adsorption method, as a key technical module for stable adsorption, agile movement and load-lifting of wall-climbing robots, is crucial for improving the overall performance of wall-climbing robots,at the same time, improvements in adsorption methods can further promote the miniaturization and lightweight of wall-climbing robots. The existing adsorption methods of wall-climbing robots were analyzed and summarized. The key technologies of the adsorption methods of wall-climbing robots were proposed and analyzed, including the trade-off between adsorption mode and movement mode, customized design of key components, optimal design supported by theoretical analysis and simulation analysis, the new materials development and simplified preparation process. An outlook on the development trend of miniaturization, light weight and large load of the adsorption methods of wall-climbing robots was made.