In order to verify the ,222,Rn concentration in the vertical distribution of possible, the validation study was carried out using the method of passive measurement of ,222,Rn, active carbon box method. Experimental results indicate that the ,222,Rn concentration decreases from 73.12 Bq/m,3, to 51.89 Bq/m,3, when the height above the ground increases from 0.04 m to 3.01 m. The vertical distribution,222,Rn concentration decreases with increasing height, was preliminarily verified. Subsequently, another experiment was taken in the same room, and the result identified the conclusion. This study could supply the dose assessment of people working in the underground construction with some guidance.