This study presents an innovative design for a heavy-load climbing robot (HLCR), specifically engineered for operation on large-scale steel structures. Utilizing a framework-based electromagnetic adhesion system, the robot’s static mathematical model was developed to accurately predict its load-bearing capacity and adhesion force requirements, ensuring stability and preventing slippage during high-load operations on steel frame surfaces. The model effectively balances forces, including magnetic attraction, robot weight, and frictional resistance. Experimental validation demonstrated a load-bearing capacity ranging from 53 kg to 54 kg, which is higher than the model’s predicted load capacity of 50 kg. The robot achieved an optimized load-bearing capacity of 50 kg, maintaining a consistent movement speed of 5 mm/s and an obstacle-crossing height of 90 mm, thereby confirming its structural adaptability and operational safety. The results highlight the robot’s capability to support heavy-load maintenance equipment while ensuring stability across various motion modes. This research addresses the increasing demand for maintenance automation in industrial and infrastructure applications.