Abstract: In modern times, the mechanical and aero forced frequency on aero-engines become more and more intricate, so dynamical interaction of different structures should be taken into account in aero-engine vibration analysis. For above reasons, a rotordynamic analysis of a whole engine model based on three-dimensional solid element was performed using the program which could take gyroscopic moment into account on NASTRAN. An unbalance response calculation of the casing was performed to predict the transfer function (dynamic stiffness) at the bearing support, as well as their effects on rotordynamics. In the analysis of models based on different elements, the effect of corner stiffness between shafts and disks was compared, as well as the coupled vibration of disks and shafts, it is proved that various vibration modes could be accurately calculated using the whole engine model based on solid element.A phenomenon of the coupled rotor bending and casing vibration was captured, as well as the effect rule, it was showed the third rotor critical speed of the coupled rotor bending and casing vibration mode was a frequency range. The method to predict critical speeds and mode shapes of the rotor considering dynamic interaction between the rotor and casing was investigated.