Abstract: With the advantages of small size, light weight, flexible design and excellent frequency selectivity, surface acoustic wave devices are widely used in radar, communication, non-destructive testing, electronic countermeasures, TV signal processing and other fields. For exploring the application of surface acoustic wave (SAW) devices in mass sensing, the Love wave propagation in a piezoelectric layered structure is systematically investigated from perspectives of theoretical analysis and numerical examples. As for the theoretical model consisting of an additional mass layer, a piezoelectric sensing layer and a semi-infinite elastic half-space, the exact solution that simultaneously satisfy the dynamic governing equations and the continuous conditions between layers is established, and the phase velocity of Love waves is obtained.Then,the three-layer structure is degenerated into two-layer structure by stepwise degradation method, and the correctness of the theory is verified by comparing with the results of previous paper. After validation, the influence of structural and material parameters of the additional mass layer on Love wave phase velocity is conducted, including the thickness, shear modulus, density, and dielectric coefficient. Finally, an approximate method with only consideration of the inertial effect of the additional mass layer is developed, with its applicable condition demonstrated. It is revealed via numerical examples that the Love wave is very sensitive to the thickness of the additional mass layer, while the dielectric coefficient has minimal influence on the phase velocity. Additionally, the phase velocity decreases linearly when the density of the additional mass layer increases. The approximate method proposed in this paper exhibits good universality, which simplifies the wave solving, and can possess high computational accuracy when the additional mass layer is thin. The results and methods in this paper can provide guidance for the application of SAW devices in mass sensing.