In the real marine environment, due to the existence of the wave field，the simple uniform flow is less, and it is necessary to study the effect of uniform flow and oscillatory flow on the oscillating cylinder. For this reason, the hydrodynamic characteristics of oscillating cylinder were analyzed by changing the intensity of oscillating flow and the amplitude ratio of the moving cylinder on the basis of validating the numerical method. The results show that the variation law of the lift coefficient is affected by the intensity of the oscillation flow and the amplitude ratio of the cylinder; when oscillation flow is weak and the amplitude ratio of the cylinder is small, the life coefficient, the locking and the beat are similar to the uniform flow; when oscillation flow is strong, the magnitude of the lift coefficient is always large and the vortex shedding in the wake is not obvious.