In order to analyze the surface acoustic wave (SAW) devices with arbitrary complex structure, and accurately and quickly characterize the multi-physical fields in SAW devices, the finite element model of the finite-length SAW device is derived by using the finite element hierarchical cascading technique(HCT) algorithm. Based on the full-wave simulation technology, the compensated-temperature leaky surface acoustic wave(TC-SAW) device with 42°Y-X LiTaO₃ is calculated considering the electromagnetic effects of the package models such as the tube holder and the bonding wire. The accuracy of the HCT model is verified by comparing with the experimental results. This work can provide support for accurate and rapid design of high performance SAW devices.