Abstract: This paper investigated the variation of dynamical response of a low pressure rotor in turboshaft engine with its system parameters.Based on the model of low pressure rotor,a dynamical simplified model of two-disk rotor with squeeze film damper at each end was built.Its motion equations were derived.The numerical method was applied to solve the 12-dimensions differential equations.The influence of some parameters,e.g.,rotating speed,eccentricity and its phase angle,mass ratio of two disks,were analyzed.From simulation results,it can be seen that when phase difference of two disks' eccentricity is π,the two disks have their minimum vibration amplitude respectively.When their phase is identical,their vibration responses reach maximum values.The larger the mass of mid-span disk is,the larger the vibrations of two disks are.When mass of mid-span is lesser than that of overhung rotor,the response of system will decrease.