At present, there is still a lack of effective methods and devices for the calibration of humidity parameters under high temperature and pressure in China, especially for the calibration of relative humidity or water vapor content under conditions of temperature above 100 ℃, and for the calibration of dew point temperature above 100 ℃. To address this issue, a high?pressure moisture generator based on the principle of single temperature and single pressure method has been developed. The generator consists of a saturation system, an air circuit system, a constant temperature system, and a control system. The saturation system completes water vapor saturation at the set temperature and pressure; The air circuit system and constant temperature system achieve gas transmission under different pressure and temperature conditions; The control system achieves precise control of overall temperature and pressure. The standard moisture with a volume fraction of 0.5% to 15% (corresponding to a dew point temperature range of -2.8 to 110 ℃) can be ultimately produced, with an absolute pressure range from 0.1 to 1 MPa, and an expanded uncertainty from 0.50 to 0.52 ℃ (k = 2) for dew point temperature. The high?pressure moisture generator has the advantages of short stability time, high accuracy, convenient operation, and strong practicality. It can be used as a calibration humidity source under high?temperature and high?pressure conditions, and has important technical application value.