Rotordynamics is a field under mechanics, mainly deals with the vibration of rotating structures. In recent days, the study about rotordynamics has gained more importance within Jet engine industries. The main reason is Jet engine consists of many rotating parts constitutes a complex dynamic system. While designing rotors of high speed turbo machineries, it is of prime importance to consider rotordynamics characteristics in to account. Considering these characteristics at the design phase may prevent the jet engine from severe catastrophic failures. These rotordynamic characteristics can be determined with the help of much relied Finite element method. Traditionally, Rotordynamic analyses were performed with specialized commercial tools. On the other hand capabilities of more general FEA software has gradually been developed over the time. As such developed and commonly used software is ANSYS. The aim of this thesis work is to build a RM12 Jet engine rotor model in ANSYS and evaluate its rotordynamic capabilities with the specialized rotordynamics tool, DyRoBeS. This work helps in understanding, modeling, simulation and post processing techniques for rotordynamics analyses of RM12 Jet engine rotor using ANSYS.