A refrigerator cooling system, comprising: a refrigerant circulation flow path provided with a compressor, a condenser, a throttling device and an evaporator; a defrosting branch; and a switching device, wherein: the evaporator comprises a heat exchange core tube, the heat exchange core tube comprises a main inlet communicated with the throttling device and a main outlet communicated with the compressor, a middle section of the heat exchange core tube is provided with at least a middle inlets, a section of the refrigerant circulation flow path between an exhaust port of the compressor and the main inlet of the evaporator is a first flow path section, wherein both the condenser and the throttling device are located on the first flow path section, the defrosting branch is connected among the exhaust port of the compressor, the main inlet and the at least one middle inlets, the switching device is for switching the defrosting branch to communicate the exhaust port of the compressor with at least one of the followings: the main inlet and the at least one middle inlets, to enter a defrosting working mode, and the switching device is further for switching the first flow path section to be in a circulating state, to enter a cooling working mode. a refrigerant circulation flow path provided with a compressor, a condenser, a throttling device and an evaporator; a defrosting branch; and a switching device, wherein: the evaporator comprises a heat exchange core tube, the heat exchange core tube comprises a main inlet communicated with the throttling device and a main outlet communicated with the compressor, a middle section of the heat exchange core tube is provided with at least a middle inlets, a section of the refrigerant circulation flow path between an exhaust port of the compressor and the main inlet of the evaporator is a first flow path section, wherein both the condenser and the throttling device are located on the first flow path section, the defrosting branch is connected among the exhaust port of the compressor, the main inlet and the at least one middle inlets, the switching device is for switching the defrosting branch to communicate the exhaust port of the compressor with at least one of the followings: the main inlet and the at least one middle inlets, to enter a defrosting working mode, and the switching device is further for switching the first flow path section to be in a circulating state, to enter a cooling working mode. the evaporator comprises a heat exchange core tube, the heat exchange core tube comprises a main inlet communicated with the throttling device and a main outlet communicated with the compressor, a middle section of the heat exchange core tube is provided with at least a middle inlets, a section of the refrigerant circulation flow path between an exhaust port of the compressor and the main inlet of the evaporator is a first flow path section, wherein both the condenser and the throttling device are located on the first flow path section, the defrosting branch is connected among the exhaust port of the compressor, the main inlet and the at least one middle inlets, the switching device is for switching the defrosting branch to communicate the exhaust port of the compressor with at least one of the followings: the main inlet and the at least one middle inlets, to enter a defrosting working mode, and the switching device is further for switching the first flow path section to be in a circulating state, to enter a cooling working mode.