A research on the internal structure of the blade with equal strength was pressented.The research was based on bi-directional evolutionary structural optimization (BESO) method and ANSYS platform.In the topology optimization process of the internal structure of the blade

a method of stress reference on middle face was proposed to simplify the optimization model.Some special technical problems in the application of BESO were also solved.Finally

an optimized topological form of internal structure of the fan blade with equal strength was obtained.The results can provide a reference for the lightweight design of the aero-engine.