Low-temperature air source heat pump device and method thereof capable of realizing water vapor conversion

The invention discloses a low-temperature air source heat pump device and a method thereof capable of realizing water vapor conversion. The low-temperature air source heat pump device comprises a compressor (1), an indoor heat exchanger (3) and a gas-liquid separator (6), wherein an outlet of the gas-liquid separator (6) is connected with an inlet of the compressor (1); and the device further comprises an air/water vapor energy collector (2) and a four-entrance/exit commutator (7). According to the low-temperature air source heat pump device, two types of heat sources including air energy and water vapor energy can be utilized; after operation is switched into a water vapor energy collection working mode, a lot of coarse granule pollutants and a few of fine granule pollutants in the air can also be removed, so that the low-temperature air source heat pump device has a certain active effect on air purification and atmospheric environment protection; and meanwhile, the low-temperature air source heat pump devic