.It is important to study the dynamic amplification effect of deep water long pile wave current to guide the selection of long pile and offshore operation. In this paper, a numerical model of fluid-structure coupling dynamic response analysis of a 100m long pile in deep water in the South China Sea is established based on pool test and verification. The dynamic response characteristics of long pile in deep water under wave and current load are calculated and analyzed. The results show that due to the hydrodynamic nonlinear effect, the numerical analysis results are somewhat conservative. The resonance effect caused by random waves causes the longitudinal motion of long piles and the dynamic amplification coefficient to increase obviously, while the superimposed flow has a certain degree of inhibition effect on the motion of long piles, and the motion reduction range is close to 30%.