To address the performance degradation of air source heat pumps in low-temperature environments, this paper proposes an air source heat pump system featuring quasi-two-stage compression coupled with an energy storage device. The energy storage device is a phase change heat accumulator that uses phase change materials to absorb or release large amounts of latent heat during the phase change process. This allows for efficient heat storage within a relatively stable temperature range. Key parameters, including heating capacity, coefficient of performance (COP), refrigerant mass flow, exhaust temperature, and system energy efficiency at different ambient temperatures, were experimentally tested. The economic performance of the system was also analyzed. Experimental results revealed that with decreasing ambient temperature, both the refrigerant mass flow rate and heat production significantly reduced. However, when compared to conventional systems with economizers, the proposed quasi-two-stage compression and energy storage coupling system demonstrated superior performance in terms of COP, heat generation, even in harsh ambient temperatures. At an ambient temperature of -30 ℃, the COP, heat generation, and the exergic efficiency of the coupled system increased significantly by 39.9%, 43.46%, and 41.8%, respectively. The daily operating costs were reduced by 4.63 yuan, including an 11% reduction under cold weather conditions, showcasing the system's economic feasibility and strong market competitiveness. In addition, in the ambient temperature range of -5 ℃ to -30 ℃, the exhaust temperature was lowered by 4.55—12.78 ℃, while the refrigerant mass flow rate increased by 11.8%—48.7%.