The invention discloses a method for monitoring and evaluating the irradiation damage of reactor pressure vessel steel in a nuclear power station. The method comprises the following steps: determining and recording the upper limit of the upper limit critical value of the nil-ductility temperature (RTNDT) and the lower limit of the lower limit critical value of the upper platform energy (USE) of a reactor pressure vessel; measuring to obtain a magnetic suspectibility x of a monitored part, subjected to irradiation damage, of the reactor pressure vessel at any point in time; computing the real-time nil ductility temperature RTNDT, real-time upper platform energy, real-time tensile strength Rm and real-time yield strength Rp0.2 of the reactor pressure vessel during the process of irradiation damage; performing analysis and evaluation on the irradiation damage degree of steel of the reactor pressure vessel according to the lowering speed of the magnetic suspectibility and the obtained RTNDT, USE, Rm and Rp0.2. According to the method, real-time and multiple nondestructive measurements can be performed, the data is accurate, the testing operation is good in safety, and further the irradiation damage degrees of multiple positions of the reactor pressure vessel can be monitored at the same time.