Abstract: The impacts of the thickness, the specific acoustic impedance and the mechanical loss factor of the backing on the performance of the thickness mode piezoelectric transducer is systemically studied, which is focused on the effective electromechanical coupling coefficient and the mechanical quality factor near the center frequency. The results show that with continuous increasing of the backing thickness, the effective electromechanical coupling coefficient and the mechanical quality factor is found rapidly declined by oscillation way. With the increase of the difference value of the acoustic impedance between the backing material and the piezoelectric material, the effective electromechanical coupling coefficient deceases and the mechanical quality factor increases. Under condition that the thickness of the backing is fixed, the effective electromechanical coupling coefficient is found declined with the increase of the mechanical loss factor by monotonous way the mechanical quality factor has minimum value and the electric characteristic curve tends to be smooth in a given frequency range. The equivalent circuit theory result is compared with the finite element method and the test results, which are in good agreement. The work mentioned above provides a theoretical guidance for the design and experimental fabrication of the sidewall ultrasonic imaging well logging transducer.