Abstract: Pressurization is proved to be an efficient way for raising the adsorption of radon on activated carbon, but the temperature and humidity variations accompanying pressurization are bad for radon adsorption. Thus, the high-pressure activated carbon adsorption system was designed and constructed to adsorb radon with controlling of temperature and humidity, five situations of environments were simulated for carbon adsorption, and the dynamic adsorption coefficient of radon was determined. By increasing the system pressure, reducing the relative humidity and temperature of adsorption, the dynamic adsorption coefficient of radon is improved exponentially. The dynamic adsorption coefficient under high-pressure, low temperature and low humidity state (0.6 MPa, 0 ℃, 20%-24%) is 5 times of that under normal pressure and temperature and humidity state (0.1 MPa, 28 ℃, 54%-65%). This research lays the foundation for future systematic research of pressurized radon adsorption relevant factors and development of efficient radon reduction facility.