Background: Canned nuclear coolant pump is welded to the steam generator and main pipe line. The pressure fluctuation generated in the pump may affect both the steam generator and main pipe line. Purpose: The research was conducted for the purpose of studying the characteristics of pressure fluctuation at inlet and outlet of the nuclear coolant pump. Methods: The frequency spectra of pressure signal located at inlet and outlet of the nuclear coolant pump were obtained with CFD(Computational Fluid Dynamics). Results: The result showed that the pressure fluctuation of the inlet position was dominated by the blade passing frequency

and the pressure fluctuation of the outlet position was much more complex. It was influenced by not only the blade passing frequency but also the axis frequency. The counter-flow in the diffuser and flow separation also influenced the outlet pressure fluctuation. Conclusion: CFD is suitable for canned nuclear coolant pump pressure fluctuation analysis.