Abstract: A state-time spectrum of aircraft ambient vibration is an important statistical parameter of an aircraft. It is an essential precondition for inducing ambient vibration data of an aircraft with the state inductive method.This paper puts forward a compiling method of the state-time spectrum of aircraft ambient vibration. It is based on a great deal of statistical data taking both flight and ground tests into comprehensive consideration. Therefore. the state-lime spectrum of aircraft ambient vibration drawn up by this method can give true expression oi the aircraft practice.This method has found engineering application.