Steam turbine power generation system and low-pressure steam turbine rotor

A steam turbine power generation system, comprising a high-pressure turbine, an intermediate-pressure turbine and a low-pressure turbine, wherein the intermediate-pressure turbine has an inlet steam temperature of 650-720°C, and the low-pressure turbine has an inlet steam temperature of 410-430°C; and a low-pressure turbine rotor of the low-pressure turbine is made of a heat-resisting steel which contains, in weight percent, C: 0.28 or less, Si: 0.03 or less, Mn: 0.05 or less, Cr: 1.5 to 2.0, V: 0.07 to 0.15, Mo: 0.25 to 0.5, Ni: 3.25 to 4.0, and the balance of Fe, unavoidable impurities and unavoidable gases, and the unavoidable impurities contain, in weight percent, P: 0.004 or less, S: 0.002 or less, Sn: 0.01 or less, As: 0.008 or less, Sb: 0.005 or less, Al: 0.008 or less and Cu: 0.1 or less.