The invention discloses a seasonal thermal storage solar low-temperature thermal electricity generation composite ground-source heat pump system. The system consists of a solar thermal collector, a ground heat exchanger, a first heat exchanger, a second heat exchanger, a third heat exchanger, a booster pump, an expansion machine, a generator, a ground-source heat pump cold and hot water unit, an electrical storage device and the like, wherein the first heat exchanger, the second heat exchanger, the booster pump, the expansion machine and the generator form an organic Rankine cycle low-temperature thermal electricity generation device; the solar thermal collector collects solar energy all the year round, in a non-heat supply period, the collected solar heat is used as a heat source of the low-temperature thermal electricity generation device by the first heat exchanger, cold is obtained from soil by a thermal storage series soil heat exchanger and is used as a cold source of the low-temperature thermal electricity generation device by the second heat exchanger, and the heat of condensation is stored in the soil. The system is applicable to civil architectures and office buildings in a severe cold area, and is particularly applicable to regions, which are far away from a centralized heating heat pipeline, are strict in atmospheric environment requirements and have frequent outage, of the severe cold area.