Taking piezodriven precision flow control valve spool and the flow field around it as the research object,the finite element model was established,and fluidstructure interaction of valve spool and the flow field around it were analyzed by using Workbench platform.Flow field analysis was carried out for flow domain by Fluid Flow (CFX) module firstly to obtain the distribution of internal fluid pressure field when valve is in steady state,then the fluid analysis results was introduced into Static Structural (Ansys) module，static analysis was carried out for spool solid domain to obtain the static deformation and Von Mises stress of spool under the fluidstructure interaction.According to the results of fluidstructure interaction analysis,the spool structural parameter was optimized . The optimization results show that under the condition of ensuring the reliability of the spool,the volume of spool is decreased by 135% and the goal of volume lightweight is achieved.