Abstract: Underground low-background laboratories have great demand in radon reduction in creating a low-radioactive background environment. A kind of principle radon reduction device was developed. KC-6 activated carbon was selected as the object of study. The dynamic adsorption coefficient of activated carbon to radon was measured at -50 ℃ to 25 ℃ using continuous air inlet method. The experimental results show that the dynamic adsorption coefficient of activated carbon has an exponential relationship with the absolute temperature in this temperature range. The decrease of temperature can significantly improve the radon adsorption ability of activated carbon. Under the temperature of -48 ℃, the activated carbon has a dynamic adsorption coefficient of 171.4 L/g, which is 20 times higher than that in room temperature condition. In addition, the adsorption heat of KC₆ activated carbon is calculated to be (20.5±1.7) kJ/mol.