The invention relates to a transverse body acoustic resonator, a preparation method thereof and an oscillator using the transverse body acoustic resonator, and belongs to the field of an MEMS (micro electro mechanical system). The transverse body acoustic resonator is restrained to move up and down, and left and right, through a fixed end; and after the resonator and a driving electrode form an electro-mechanical coupling system by vertically arranging the resonator, when the electro-mechanical coupling system is driven by an external force, the resonator is only retracted and deformed in the horizontal direction, so that the vibration mode is single and stable, and stable frequency can be achieved when the oscillator using the the structure works. During preparation of the resonator, a suspension resonator, the fixed end and the nano level interval driving electrode are formed by a silicon wafer front surface etching process together with a depositing and bonding process, a wet etching process and the like, so that the height and the thickness of the suspension resonator and the clearance of the driving electrode can be effectively controlled.