Physiological effects caused by power ultrasound irradiation are of therapeutic benefits for fracture healing, but sometimes will cause tissue damage. However, these effects are hard to detect by current instruments. The aim of this study is to analyze the behavior of the cancellous bone subject to therapeutic ultrasonic vibration excitation. In this work we adopted a three-dimensional Finite Element Method (FEM) as a virtual measurement tool to study the acoustic-radiation-induced stress fields inside and on the surface of bone to predict the biological effects of ultrasound. The existence of soft tissue was involved in our model construction and the interface between bone and muscle was processed with coupling method. The ultrasound power propagation from muscle to bone was simulated with FEM. The ultrasound radiation was generated by a 2-MHz excitation, and was applied on the surface of soft tissue. In this study, we defined 6 paths of different bone layers to study stress distributions and Coefficient of Variation (CV), and the stress in muscle was also worked out to make comparisons. Simulation results show that the middle bone tissue has a higher mean stress (2027.7 Pa) than the surface (763.3 Pa) and outer layer (1898.1 Pa). Moreover the stress distribution of middle layer is less disturbed (CV = 39.8%).