The force on the balance elbow is complex and variable.The virtual simulation of the moving part was carried out by Adams, and the real load of the balance elbow could be obtained by combining with the entity calculation, which is about 35 kN. According to the analysis of fatigue theory, the service life of the initial structure of the balance elbow is over 130 000 km.In order to realize the lightweight of the balance elbow, the topology optimization of the structure was carried out. By means of circular groove design at the end face position of the balance elbow connecting the torsion bar.The method was to design the circular groove in the position of the end face of the balance elbow connecting torsion bar.The result shows that under the same force, the weight of the balance elbow is reduced by 5 kg and the service life is guaranteed.The loss of titanium alloy material is reduced and the development cost is saved by the structure topology optimization.