The invention provides a double-heat-source heat pump system. The double-heat-source heat pump system comprises a compressor, a condenser, a throttling component, an economizer, an evaporator, an air and liquid separator, a heating device, a check valve and a bypass pipeline, wherein the compressor is provided with a middle air replenishing hole; the bottom of the condenser is higher than the top of the heating device; an exhaust hole of the compressor communicates with an inlet of the condenser; an outlet of the condenser communicates with a first inlet of the economizer; the outlet of the condenser communicates with a second inlet of the economizer through the throttling component; the outlet of the condenser communicates with the inlet of the heating device through the check valve; the outlet of the heating device communicates with the middle air replenishing hole of the compressor through the check valve; the outlet of the heating device communicates with the inlet of the condenser through the check valve; a second outlet of the economizer communicates with the inlet of the heating device; a first outlet of the economizer communicates with the inlet of the evaporator through the throttling component; and the outlet of the evaporator communicates with an air sucking hole of the compressor through the air and liquid separator. The double-heat-source heat pump system provided by the invention has the advantages of reasonable structure, high performance cost ratio, excellent low-temperature characteristics and the like.