The invention belongs to the field of power generation of steam turbine generator units and discloses a secondary reheat system adopting solar energy cooperating with a steam turbine generator unit. The secondary reheat system comprises a solar energy reheat module, a low-pressure cylinder, a medium-pressure cylinder, a high-pressure cylinder and a generator; the medium-pressure cylinder is connected with the high-pressure cylinder and the low-pressure cylinder, the solar energy reheat module is connected between the medium-pressure cylinder and the low-pressure cylinder, and the generator isconnected with the low-pressure cylinder; the solar energy reheat module comprises a solar energy heat collecting field, a cold pump, a heat pump and a heat exchanger; one end of the solar energy heatcollecting field is connected with the cold pump, the other end of the solar energy heat collecting field is connected with the heat pump, and the cold pump and the heat pump are connected with the heat exchanger simultaneously; and in addition, a cold buffer tank is arranged between the cold pump and the heat exchanger, and a heat buffer tank is arranged between the solar energy heat collectingfield and the heat pump. Through the secondary reheat system, the technical problems that boiler secondary heating is adopted, thus pipeline arrangement is complex, and the heating area of a hearth islarge are solved, meanwhile, the exhaust humidity of the low-pressure cylinder is decreased, the absolute efficiency of the low-pressure cylinder is improved, and the solar energy photovoltaic efficiency is improved.