The invention discloses a new energy automobile ultralow-temperature heat pump air conditioner system and a control method. The modes of refrigerating, heating, dehumidifying and defrosting can be achieved by adjusting the loop connecting modes, and the characteristic of simple and stable loop structure is achieved. In the heating mode, two refrigerant travelling paths are formed, the workload of an automobile external heat exchanger is reduced, enthalpy of a compressor is increased, the working efficiency of the compressor is effectively improved, and the reliability of the system is ensured; in the refrigerating mode and the defrosting mode, direct communicating bypasses are used for avoiding unnecessary parts, refrigerant pressure drop can be reduced, and flow resistance is reduced, so that load of the compressor is reduced, and the working efficiency of the compressor is improved; and the opening mode of the bypasses is flexible, control is easy, adaptability regulation can be conducted according to actual using conditions, and the using range is enlarged.