To address the issues of low work efficiency, high cost, and significant safety risks associated with traditional bridge pylon painting operations, a negative-pressure wall-climbing robot adaptable to high-altitude work on the outer wall of bridge pylons was designed and developed. To ensure the stable adsorption of the wall-climbing robot at the specified working height, the wind-loaded environment encountered by the robot during high-altitude operations on bridge pylons was simulated, and the corresponding aerodynamic six-component force coefficients of the robot were obtained. Force analysis of the wall-climbing robot during its operation on bridge pylons was conducted to determine the minimum adsorption force required for the robot to achieve stable adsorption under wind load conditions, as well as to calculate key parameters of the negative-pressure generating device, including air volume, wind pressure, rotational speed, and power. To improve the adsorption stability of the wall-climbing robot, the structural shape of the negative-pressure chamber was optimized. Fluid simulations were performed using Fluent software to investigate the influence of different factors of the negative-pressure chamber on the adsorption force under wind load conditions, and the theoretical relationships between the ground clearance of the negative-pressure chamber, the thickness of the negative-pressure chamber's partition layer, and the adsorption force were obtained when the robot was subjected to wind loads. Finally, based on the simulation results, the structure of the negative-pressure chamber was optimized and an experimental prototype was built. Experimental tests were carried out on the adsorption stability of the optimized wall-climbing robot, which verified the correctness of the theoretical and simulation analyses and provided a theoretical basis for the structural design of negative-pressure adsorption wall-climbing robots.