Magnetic Resonance Elastography (MRE) is a noninvasive technique to measure elasticity of tissues in vivo. In this paper, a mechanical shear wave MR imaging system experiment is set for MRE. A novel actuator is proposed to generate mechanical shear waves propagating inside a gel phantom. The actuator is made of piezoelectric ceramics, and fixed on a plexiglass bracket. Both of the gel phantom and the actuator are put into a head coil inside the MR scanners bore. The actuator works synchronously with an MR imaging sequence running on the MR scanner. The sequence is modified from a FLASH sequence into a motion-sensitizing phase- contrast sequence for shear wave MR imaging. Shear wave images are presented, and these effects on the shear wave MR imaging system, including the stiffness of phantoms, the frequency of the actuator, the parameters of the motion-sensitizing gradient, and the oscillation of the patient bed, are discussed.