In this paper, the effect of thickness of each component for 50 MHz ultrasound transducer was investigated based on the finite element model (FEM).A reasonable finite element model has been established, and the sound fields and vibration characteristics in different conditions have been obtained by simulation. The results show that adding a match layer can improve the sound penetration transmission and has great influence on the admittance curve on which another resonant frequency appears; and the optimum thickness of match layer is 13.5 μm for 40 μm piezoelectric disc.The analysis of effect of thickness of backing layer shows that it can improve the sound field characteristic and the admittance curve at some extent, but the change of its thickness has small influence on the sound field.