Abstract: It is always difficult to perform aeroelastic analysis onturbomachinery efficiently and precisely due to the complexity of the flowfield and structures. The authors develop an unsteady aerodynamicReduced-Order-Model (ROM) which can be used on small amplitude vibratingblades of turbomachinery. Based on this ROM and classic energy method, anefficient method on aerodynamic damping coefficient calculation forturbomachinery is introduced. With this method, only one unsteady CFDcomputation is needed to calculate the aerodynamic damping coefficients atall Inter Blade Phase Angles (IBPA) under one specific modal and frequency.The aeroelastic characteristics of STCF4 and NASA Rotor 67 are analyzed byusing this ROM with classic energy method. The numerical results indicatethat the aerodynamic damping coefficients attained by ROM and unsteady RANSmethod agree well with each other in the condition of small amplitude ofvibration. The efficiency is improved by almost 10 times than multi-passagesRANS method. In addition, this ROM can be used in aeroelastic analysis withmistuning effects.