Heat pump units are widely used in air conditioning systems in large buildings, good ventilation and heat dissipation conditions are required to ensure their good working conditions. Acoustic enclosures are the most important ancillary facilities of heat pump units, the internal air circulation and heat dissipation of the acoustic enclosure was always ignored, causing the reduction of heat exchange performance. By establishing a finite element model of the flow field based on the speed inlet and outlet, the temperature field of a specific type of heat pump unit’s acoustic enclosure was analyzed, and the temperature fields with and without airflow channels were studied. The results showed that the intake and exhaust airflow were separated effectively by the airflow channels and the temperature of the intake airflow was prevented from rising continuously due to the backflow of gas. This study provides an engineering reference for the heat dissipation design of the heat pump units’ acoustic enclosure.