Fatigue widely exists in the industrial structures and is a common reason for structural failure. Monitoring the fatigue process of some key parts has significant meaning for avoiding material fracture. The Magnetic Barkhausen Noise (MBN) method for ferromagnetic material fatigue state evaluation is presented in this paper. Q345 carbon steel used in pressure vessel is studied with stress control in high cycle fatigue process. The MBN signal response to different exciting frequencies during the fatigue process is specially investigated. The waveform, frequency spectral, RMS and peak amplitude of MBE signals were analyzed. The RMS vs fatigue cycle curves show a stepladder characteristic. It illustrated that MBE signals have great potential to indicate the fatigue state of ferromagnetic material.