Abstract: An analysis of the steady-state unbalance response of a dual-rotor gas turbine engine with a nonlinear flexible intershaft squeeze-film damper is implemented using a simplified transfer matirx method with rotating coordinates.The simplified transfer matirx method is convenient for evaluation of the critical speed and the steady-state response of the rotor system with various supports, shaft coupling, intershaft bearing, etc. The rotating coordinates are simpler than the fixed Cartesian coordinates for calculation of oil film force generated by the centralized squeeze film damper. The nonlinear characteristcs of the squeeze film damper are calculated by using iteration method.The introduction of a flexible intershaft squeeze film damper into the rotor system is effective in reducing amplitude response and bearing loading, especially at the location of the intershaft bearing and adjacent rotor bearing supports.