Against the background of RPV irradiation embrittlement,this paper introduces the principle of Barkhausen noise detection and the design of detecting system of RPV irradiation embrittlement.Experiments are carried out to research effects of excitation signals frequency on Barkhausen noise detection.It draws conclusions that delay time produced by Barkhausen noise increases along with the raise of excitation frequency.The RMS of Barkhausen noise signal firstly increases then decreases with the increase of excitation frequency.