The invention belongs to the technical field of mechanical part design, and discloses a bridge crane main beam lightweight design method, which comprises the following steps of: acquiring cross section data of a crane main beam as a design variable, and taking weight reduction of the crane main beam as an optimization target; generating constraint conditions based on the vertical static stiffness, the normal stress, the
shear stress, the fatigue strength and the overall stability to construct a crane girder section model; carrying out design variable coding on the crane main beam section model based on an improved grey wolf optimization
algorithm, carrying out initialization setting, selecting a first wolf by constructing a
fitness function, introducing adaptive update
control parameters, updating the position of a grey wolf in a
population, and when a termination condition is met, carrying out self-
adaptive optimization on the grey wolf; and outputting the potential solution corresponding to the
gray wolf position as an optimal solution. Based on the crane main beam section model and the improved grey wolf optimization
algorithm, the intelligent lightweight design of the crane main beam is realized, the scheme design efficiency is improved, and the crane manufacturing cost is effectively reduced.