Abstract: When one end of a fluid-filled pipe with an elastic wall is fixed and a harmonic force effect acts on the other end, a steady longitudinal vibration will be produced. Compared to the pipeline resonance mode, the amplitude of the steady longitudinal vibration of an elastic pipe is greater, and the effect on the sound is also greater. The study of the steady longitudinal vibration of pipes can better describe the effects of fluid-filled pipelines on the radiation sound field of the pipe opening. Through the contrast between the analysis calculation of the equivalent beam model and the experimental results, the accuracy of the equivalent beam model for the calculation of the steady longitudinal vibration of pipelines is verified, and a method of isolating the steady longitudinal vibration state is proposed and verified.