Abstract: Specimens of domestic nuclear reactor pressure vessel（RPV） steel were irradiated using 240 ke V protons with fluence ranging from 0.25 to 5×1017 cm-2（0.05 to 1.0 dpa） at room temperature. The measurement of the Magnetic Barkhausen Noise（MBN） and Vickers microhardness tests were conducted to explore the relationship between the MBN and irradiation fluence, mechanical properties. The results showed that the MBN signal was very sensitive to irradiation-induced defects. With the increase of irradiation damage the MBN signal initially decreased rapidly and reached the minimum at about 0.22 dpa. Then it increased and finally had no obvious change in the range of 0.3 to 1 dpa. These changes may be mainly attributed to the interaction between magnetic domain wall and irradiation-induced defects. The Vickers microhardness test indicated that there exists a remarkable radiation hardening tendency after proton irradiation. Meanwhile, a significant linear correlation between the MBN and Vickers microhardness was obtained.