Milling thin walled structures is challenging due to their low stiffness and hence consequential vibration problems. So some measures need to be taken to suppress chatter. Based on the vibration absorption principle of tuned mass damper (TMD), the vibration suppression auxiliary fixture is designed according to the finite element analysis and modal experiment results. The proposed auxiliary fixture does not require additional power unit, with simple structure, easy installation,flexible and convenient advantages and can be widely used in industrial manufacturing. The experimental results show that the amplitude of the low frequency vibration of the system reduced by 90%, the amplitude of the high frequency vibration reduced by 70%, and the coupling vibration amplitude of the tool and the workpiece reduced by 80%.