The invention discloses a low temperature resistant fuel gas heat pump air-conditioning system combining awaste heat recovery mode and a liquid dehumidification mode. The system mainly comprises a gas engine (1), a compressor (2), a hot water waste heat recovery device (3), a four-way reversing valve (4), a heat exchanger (5), a throttling valve (6), a heat exchanger (7), a liquid storage tank (8), a solution heat exchanger (9), a preprocessor (10), a dehumidifier (11), a fan coil (12), an oil separator (13), a cooling water circulating pump (14), a chilled water circulating pump (19), a solution pump (20) and a heat insulation plate (23), which form four subsystems, namely a refrigerant system, a chilled water system, a cooling water system and a liquid dehumidification system, and the flow direction and the flow rate of a medium are regulated through valves; in summer, a dilute solution is heated by enginewasteheat and condensation heat to concentrate, so as to form a temperature and humidity independently controlled dehumidification link; in winter, the enginewasteheat is used for improving the temperature of an evaporator heat transferring medium, so as to improve the machine set COP (Coefficient Of Performance). According to the low temperature resistant fuel gas heat pump air-conditioning system, the gas engine waste heat can be used effectively, the energy consumption in operation is reduced, and the adaptability of the system tothe low-temperature environment is enhanced.