The offshore boarding trestle is a structure that connects the offshore platform or offshore wind turbine to provide safe passage for operators.In this paper, considering the dead weight of the structure, live load, wind load, acceleration load and environmental load, workbench is used to analyze the staircase of the trestle at sea, and the displacement cloud diagram and comprehensive stress cloud diagram of the ladder are obtained.Through three different response surface types, taking the quality as the optimization objective, displacement and comprehensive stress as the constraint conditions, the multi-section size optimization of the ladder is carried out.On the premise of meeting the strength requirements, the engineering materials are saved, the price cost is reduced, and the economy is improved. It provides a reference for lightening the trestle and avoiding excessive design.