Abstract: The finite element model of the bend pipes conveying fluid is established to explore the dynamics of the fluid-filled pipe in a spacecraft energy supply system. Modal analysis of the fluid-filled pipe is executed to study the effects of thickness,diameter and bending angle of the pipes on the natural frequency. On the other hand,a length of pipe conveying fluid in a proton exchange membrane fuel cell system is selected to analyze the impact of the unsteady flow of pipes fluid on its dynamic properties. The influences of the installed position of valve and pipe's thickness on the value of pipe's displacement and stress are studied. Numerical results show that the fluid-structure interaction(FSI) causes a reduction of the natural frequency of pipes. With increasing pipe thickness,the pipe natural frequency increases. The pipe diameter and bending angle have a less important effect on the low order natural frequency of pipes,while the effect should be taken into account on the high natural frequency. The smaller the material stiffness is,the greater the influence on the FSI becomes. Meanwhile,the unsteady flow of the fluid can result in jumping of the wall displacement and stress. The installation position of valve has little effect on the amplitude of the pipe's displacement and stress; however,the stress position changes with its extreme. With increasing pipe thickness,the amplitude of pipe displacement and stress decreases.