Abstract: Aiming at the optimization of clamping performance of hydraulic expansion fixture, the influence of different structure and matching parameters of a hydraulic expansion fixture system on workpiece clamping deformation, clamping moment and locking stiffness was analyzed by finite element software, and above parameters were optimized and analyzed by multi-objective optimization method. The results show that by adjusting the structure and matching parameters of the hydraulic expansion sleeve fixture, the clamping performance of the hydraulic expansion fixture has been significantly improved. The clamping deformation of the middle part of the workpiece has been reduced from 12 to 3.2 μm, the clamping deformation of the two ends has been reduced from 28 to 4.8 μm, and the maximum stress of the workpiece has been reduced from 435.9 MPa to 85.7 MPa.