In this paper, the experimental and simulation methods were used to study the thermal comfort of the direct air source heat pump heating system with different heat dissipation terminals. The indoor air temperature distribution characteristics of the direct expansion air source heat pump heating system using the new thermosiphon radiator (DE-HP-T) and the traditional hot air-conditioning dissipating terminal were studied experimentally. Furthermore, the dynamic thermal environment variation of the system startup phase was analyzed. After verifying the reliability of the model, the indoor non-uniform steady-state thermal environment of the direct expansion air source heat pump heating system using different heating terminals was simulated, thermal comfort of the local and overall thermal sensation was evaluated by the equivalent temperature index. The results show that the temperature rise of the indoor air in the DE-HP-T system is fast, reaching 10.8°C/h, which is slightly less than the 13.8°C/h of the traditional hot air conditioning system; However, compared with the traditional hot air conditioning system, the DE-HP-T system can avoid the thermal discomfort caused by excessive temperature difference between the head and the foot and “cold radiation”. At same time, it can improve the thermal comfort of the human calf and the foot, and have more comfortable overall thermal sensation.