The invention relates to a hydroelectric generation device. The hydroelectric generation device comprises a machine body fixedly installed on a supporting frame, a main water storage cavity, an auxiliary water storage cavity and an installing cavity are sequentially arranged in the machine body from top to bottom, a water inlet pipe communicated with the main water storage cavity is arranged at the top of the main water storage cavity, a water outlet pipe is arranged at the bottom of the installing cavity, a first through groove for communication is arranged between the main water storage cavity and the auxiliary water storage cavity, and a second through groove for communication is arranged between the auxiliary water storage cavity and the installing cavity; and a main rotating shaft connected with a power generator is rotationally installed at the position, located on the lower right portion of the first through groove, of the center of the auxiliary water storage cavity, an auxiliary rotating shaft is rotationally installed at the position, located on the lower right portion of the second through groove, in the installing cavity, and rotating assemblies are fixedly installed onthe main rotating shaft and the auxiliary rotating shaft; and each rotating assembly comprises a rotating sleeve and a plurality of rotating hinges evenly installed at the outer end of the rotating sleeve, and the rotating sleeve is fixedly connected with the main rotating shaft and the auxiliary rotating shaft.