Abstract: In order to analyses the nonstationary vibration signal during an aero-engine's test drive process,the computed-order analysis method based on zoom and emendation method in spectrum analysis are applied.Although the engine's rotational speed changes notable and the vibration signal is seriously nonstationary,the character component's parameter is picked up precisely.The paper also provides the concrete algorithm,and then provides an analytical answer of a real example,which demonstrates the paper's method.