The LNG low temperature submersible pump is modeled by UG and the thermo-fluid-structure coupling of the rotor components are calculated by ANSYS Workbench as the platform. The thermodynamic coupling force of the flow field to the solid structure is obtained. The modes of the rotor components are analyzed with or without prestressing force. Based on the results, the first ten order modes are extracted and the modes in the two cases are compared. The results show that except for the seventh-order and eighth-order vibrations, the vibration of the other stages is expressed on the impeller; after the prestressing is added, the various modes of the rotor component do not change.But the natural frequency of each order has a slight change,the prestress has little effect on the natural frequencies of the rotor components. The natural frequency of the ninth and tenth order are close to the three times the blade frequency of the pump, so there is the danger of resonance.It is necessary to optimize the design of the rotor components so that the front three times the blade frequency can be far away from the natural frequencies of the various stages, thereby avoiding the resonance of the pump during operation. Under the influence of prestressing force, the amplitude of the rotor parts also has a small change.
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