The purpose of this paper is designing an optimal controller for vibration suppression of a funnel-shaped smart structure with distributed piezoelectric actuators and sensors applicable in Magnetic Resonance Imaging (MRI) system. This can help sensitive human beings from vibration and acoustic noise syndrome. Also, the vibration suppression in this structure prevents the test results to be damaged, which is an important issue in medical tests. For this aim, the problem of the vibration control for the funnel-shaped inlet structure of the MRI tomography is stated and the structure is described, first. Then the task of the structure modeling is tackled applying the FEM approach. Identification of the dynamic frequency response of the desired funnel is performed using the modal-based identification method and the state space model is obtained. Then, the control design for the structure is considered using LQG control method. Complete design and control development procedure is implemented in order to reduce the vibration magnitude of a funnel-shaped shell. Finally, the performance of the designed controllers in both frequency domain and time domain are compared with the open loop systems and results are discussed
