A structure for changing the propagation ways of the impact stress wave in the jet type fluid hammer is designed, and analysis shows that the attenuation degree of the stress wave changes with different propagation ways. The simulation on the hammer returnstroke is analyzed based on LSDYNA. The stress change of the fluid element is studied when the hammer impact is propagated in two different ways in the return stroke of the jet type fluid hammer. The results show that the power external transmission mechanism can greatly reduce the impact stress acting on the fluidic element by avoiding the rigid collision on the upper part of the cylinder. Moreover, the geometric parameters of the external transmission mechanism also have some influence on the stress attenuation.