Abstract: The particle-fluid composite damping technology is applied to the longitudinal vibration suppression of the ship propulsion shafting. A simulation test platform was designed and constructed, and the influence of particle damping, liquid damping and particle-fluid composite damping on the vibration reduction performance of the shafting was systematically studied. The influence laws of key parameters such as particle size, mass fill ratio, rotational speed, excitation frequency, excitation amplitude, particle/fluid mass ratio and liquid viscosity on the vibration reduction ratio of the composite damping system are researched, revealing the vibration suppression mechanism of the composite damping. The research results show that under different working conditions, the particle-fluid composite damping system exhibits a significant vibration reduction effect near the main frequency, and its vibration reduction ratio is better than that of single particle damping and single liquid damping. In the composite damping system, the viscosity of the liquid, the rotational speed and the mass fill ratio have a significant influence on the vibration reduction ratio, while the excitation amplitude is relatively small. The particle-fluid composite damping technology can effectively suppress the longitudinal vibration of the ship's shafting under different working conditions and has a good engineering application prospect.