Abstract: For satisfying calibration request of radon measure in the laboratory, the calibration apparatus for radon activity measure was designed. The calibration apparatus can run in three models: sequent mode, pulse mode and constant mode. In the paper, the stability and reliability of the calibration apparatus were tested under the three models. The experimental result shows that the apparatus can provide an adjustable and steady radon activity concentration environment for the research of radon and its progeny and for the calibration of its measure.