Abstract: structure was designed. The locking and loosening actions of the locking structure were realized by locking and loosening the brake pads through two locking plates. Static structural analysis and modal analysis of the two locking plates were carried out. Two locking plates were designed to be lightweight using topological optimisation methods. The structures before and after optimisation were compared and analysed. The results showed that the mass of the two locking plates was reduced by 23.10% and 13.93% respectively， and the first-order intrinsic frequency increased by 12.09% and 12.43% respectively. Finally，the optimised design of the locking structure was verified by experiments. The method provided a reference for the optimised design of other key components and the whole machine tool of this type.