A multi-connected air-conditioning heat pump unit with large thermal capacity essentially consists of an outdoor unit, a plurality of indoor units, a refrigerant liquid connecting tube, and a refrigerant gas connecting tube; wherein, the outdoor unit comprises a compressor, a four-way reversing valve, a heat exchanger of the outdoor unit, an electronic expansion valve of the outdoor unit, a gas-liquid separator, a liquid tube connecting valve and a gas pipe connecting valve. The heat pump unit is characterized in that an adjustor used for adjusting the refrigerant circulating volume is arranged on a gas pipe positioned between the four-way reversing valve and the gas pipe connecting valve in the outdoor unit; the adjustor used for adjusting the refrigerant circulating volume is connected with a high-pressure liquid tube arranged between the electronic expansion valve and the liquid tube in the outdoor unit via a refrigerant circulating volume adjusting tube. The multi-connected air-conditioning heat pump unit can determine an optimal refrigerant charging volume based on thermo-producing running, and can automatically provide appropriate refrigerant for refrigerating circulation based on refrigeration and thermo-producing running. The multi-connected air-conditioning heat pump unit has the advantages of remarkably raising the thermal capacity when the heat pump unit runs, improving the energy efficiency ration of refrigeration running, and having significant practical value.