In this paper, the OTEC cold water pipe is taken as the research object, the fluid-structure coupling model of the cold water pipe is established through the structural equation and the wake oscillator equation, and the time domain analysis of the vortex-induced vibration of the cold water pipe is performed by the finite element method , and the corresponding solving program is developed in the MATLAB software. In view of the complicated working conditions faced by the cold water pipe, the effects of external flow field, internal flow, aspect ratio and ballast mass on the vortex-induced vibration were studied respectively. The results show that with the increase of external flow velocity and aspect ratio, the transverse vortex-induced vibration mode and amplitude of the cold water pipe change correspondingly, and the vibration intensity fluctuates. Under the condition that dynamic instability does not occur, the increase of internal flow can effectively reduce the transverse vibration amplitude, and the ballast mass can significantly reduce the vibration displacement of the free end of the cold water pipe.