Vibration isolation of the sonic power head of is the key to ensure whether it can work safely and stably. In this paper， the forced vibration model of the power head isolation mechanism is established based on the damped forced vibration theory of the single-degree-freedom system， and it is found that the rubber stiffness k， damping c and frequency w of the external excitation force are the main factors affecting the vibration isolation performance of the power head. On this basis， the dynamic model of the power head is established to simulate its vibration characteristics. The results show that the vibration isolation transfer rate of the power head is proportional to the frequency of the external excitation force， inversely proportional to the stiffness of the vibration isolation spring， and proportional to the damping of the vibration isolation spring. When the stiffness of the spring increases to a certain value， the vibration isolation transfer rate tends to a constant value. Therefore， in practice， the vibration isolation performance of the power head can be improved by appropriately increasing the external excitation frequency and choosing rubber material with low stiffness and large damping for the vibration isolation spring. The conclusions can provide reference for setting the working frequency of the sonic drill and optimizing the vibration isolation mechanism of the power head.