In response to the challenge of achieving efficient low temperature heating performance in heat pump air conditioning systems for pure electric buses, a quasi-two-stage compression heat pump air conditioning system incorporating fully micro-channel technology is developed. A series of experimental studies were conducted to investigate the influence of different compressor speeds and fan frequencies on system performance, resulting in corresponding performance curves. In a low temperature environment of -10°C, the compressor exhaust temperature is maintained at 44.34°C. Concurrently, the system heat exchange capacity is enhanced by 11.3% to 47% compared to the non-supplemented air system. Moreover, at a compressor speed of 4000 rpm, the system COP was found to be 2.72. The implementation of variable frequency compressor speed and fan frequency in the pure electric bus heat pump system has resulted in enhanced system performance, leading to energy savings.