A　severe　oscillation,　accompanied　with　an　abnormal　＂click＂　sound,　of　a　fuel　feeding　pipe　system　during　valve　closing,　when　the　feeding　flowrate　reaches　a　certain　value,　is　observed　experimentally.　A　fluctuation　model　in　which　stiffness　and　damping　coefficients　of　the　vibration　system　are　time　varying　is　proposed.　Each　coefficient　is　composed　of　two　parts,　one　of　which　is　constant　and　the　other　is　time　varying.　Based　on　this　model,　simulation　transients　of　the　vibration　displacement,　velocity　and　pressure　in　the　pipe　are　presented.　Simulations　of　the　pressure　transients　are　compared　with　experimental　data　detected　by　pressure　transducer,　which　shows　that　both　have　fluctuations　in　the　transient　process　at　a　large　flowrate.