Multisource cleaning energy supply is a significant solution for reducing carbon emission and achieving carbon neutral. This paper proposed an integrated ground source heat pump-photovoltaic-thermal (GSHP-PVT) system to achieve the combined clean heating/cooling, reduce the heat transfer irreversible loss, and increase the flexibility of the system by introducing double-evaporators with different working fluids. According to the heating or cooling in day or night, we proposed five kinds of operation modes of the system in the annual year in winter, summer, and other seasons. Moreover, we applied the heat current method for constructing the overall heat current models of each operation mode. On this basis, the minimum of the total input work of the system can obtain the optimal mass flow rate allocation in each component under five operation modes. The optimization results show that the COP of the GSHP-PVT system always remains between 4 and 6 in the annual year. Meanwhile, the proposed system can effectively prevent the ground source?s temperature decrease and operate with high efficiency. Besides, the increase of the total thermal conductance of this system, the PVT collector areas, and the temperature of water-antifreeze flowing out of the PVT collector can effectively improve the overall performance of the proposed system.