Abstract: Aiming at the problem that the workpiece is easily deformed during the cutting process of the thin-wall part of the main model of the automobile inspection tool, the main model thin-walled part processing anti-deformation fixture is designed, and the floating auxiliary support rod is used to support the workpiece, which can be buoyant in the magnetorheological fluid. Under the action, it is adaptively fitted to the surface of the workpiece; the vacuum chuck and positioning device are designed to clamp and position the workpiece. The sliding positioning device can realize the positioning of the fixture in the space area. The clamping scheme of the vacuum chuck device can quickly replace the workpiece. It does not affect the surface processing quality and is convenient and stable; the flexibility is embodied in the fixture can be adaptively adjusted to suit the cutting process of different types of main model thin-walled parts, thereby saving the manufacturing cost of the fixture. Using computer-aided software to calculate the reasonable position of the clamping point, can ensure that the workpiece does not produce displacement and deformation during processing; the magnetorheological fluid locking device can quickly change the elastic state of the auxiliary support rod; improve the clamping efficiency of the workpiece, save man-hours and meet processing requirements.