The utility model discloses a low-pressure blade stage group of a water-cooled steam turbine used for power generation, which comprises four stage groups, wherein each group of fixed blades are welded on a diaphragm; each group of moving blades are arranged in an impeller slot on the excircle of a rotating shaft through blade roots; the exhaust area of the stage groups is 3.2m<2>; moving blade bodies of the four stage groups are free blades, wherein the first-stage moving blades are of an inverted T-shaped blade root structure; the second and third-stage moving blades are of a double inverted T-shaped blade root structure; and the fourth-stage moving blades are of an inclined fir tree blade root structure; the axial length of the stage group is 894.5mm; the root diameter of first-stage fixed blade bodies is 1120mm and the top diameter is 1592mm; and the root diameter of the fourth-stage moving blade bodies is 1120mm and the top diameter is 2240mm. The low-pressure blade stage group of the water-cooled steam turbine used for power generation has good variable working condition operating performance and strong vibration performance, is convenient to assemble and is applicable to the high-power water-cooled steam turbine unit used for power generation.