In the face of more and more serious energy and environmental problems, energy conservation and environmental protection have attracted more attention all over the world. Combining the advantages of high temperature heat pump (HTHP) and natural refrigerant, water vapor HTHP system can effectively recover low-grade energy and is more green and environmental friendly. This paper presents a new water vapor HTHP system with 80-90 degrees C waste heat recovery and 120-130 degrees C hot water supply. The water vapor HTHP system model is established to investigate the system performance under different working conditions. Then, the experimental study of the HTHP system with water refrigerant is carried out to validate the simulation results. The simulation results present that when the evaporation temperature is under 83-87 degrees C and the condensation temperature among 120-128 degrees C, the compressor power ranges from 46.1 to 58.1 kW and system COP ranges from 3.64 to 4.87. The comparison between simulation and experimental results show good agreement with each other, which indicates that the model established in this paper has great reliability and accuracy for water vapor HTHP system. (C) 2018 Elsevier Ltd. All rights reserved.