A solar power generation device, provided with a power multiplication unit (2). A solar power generator (3) is connected to and located outside of the power multiplication unit (2). The power multiplication unit (2) is provided with a parallel-shaft speed increasing device (21) having a drive shaft (22) on one side and a torsion shaft (23) on the other. The drive shaft (22) is rotatably connected to a motor (24), and the torsion shaft (23) is rotatably connected to a planetary gear torque amplifier (4). The planetary gear torque amplifier (4) is provided with an internal ring gear (41). An inner side of the internal ring gear (41) is connected to a planetary gear set (42) in a circular manner, and a power generator guide shaft (43) is fixedly connected to a side of the planetary gear set (42). The power generator guide shaft (43) is rotatably connected to a power multiplication generator (5), and is provided with planetary gears (422) at one side thereof that mesh with the internal ring gear (41) at an inner side thereof. The torsion shaft (23) is located between the planetary gears (422) and meshes with the same. In this way, the invention solves the problems of high assembly cost, short duration of effective power generation output, and an efficiency decrease caused by consumption after power is generated by a solar panel, thereby extending the effective power generation time.