In order to improve the performance of the humidification and dehumidification desalination unit,a two-stage humidification and dehumidification heat pump desalination system was proposed.The two-stage humidifier was used to recover and discharge the seawater waste heat from the first-stage humidifier,to improve the heat-mass exchange effect between seawater and wet air.Aspen Plus simulation software was used to establish the models of one-stage and two-stage humidification heat pump seawater desalination systems.Multi-condition simulation studies were carried out for different inlet seawater temperatures,liquid-gas mass ratios and refrigerant flow rate of the heat pump.According to the comparative analysis of simulation results,it is concluded that the recovery rate and water-making ratio of the two-stage humidifier system are better than that of the first-stage humidifier system with the increase of inlet seawater temperature and liquid-gas flow ratio.And the inlet seawater temperature and circulating air flow required for the two-stage humidifier system to achieve optimal system performance are lower than that of the first-stage humidifier system,indicating that the two-stage humidifier dehumidification desalination technology of the heat pump has great performance improvement and broad application prospects.