Abstract: In order to analyze the structural safety of fuel assembly for nuclear powered ships in moving state, taking the marine nuclear power platform as an example, hydrodynamics is adopted to conduct the frequency and time domain calculation for the platform to obtain the time serial curves of the center of the gravity in six degrees of freedom. Remote displacement method is used to transfer the ship motions to the reactor to realize the numerical simulation of fuel assembly moving with the ship, and transient structural mechanics is adopted to calculate the structural loads of fuel assembly finally. Results show that the structural loads of fuel assembly increase obviously in ship moving state compared with that in static state. Therefore, it is quite essential to take the ship random motion response into account during the structural safety analysis of fuel assembly.