Abstract: The Alpha active substances were absorbed from the solution by Ba~(2+) onTi~(4+) and then mixed evenly with ZnS(Ag), the precipitate was filtrated, driedsealed and measured in equipment with a photomultiplier. The detection angle is4π, the efficiency is～0. 95. This method can quntitatively detect ~(222)Rn, ~(220)Rn,and their daughters.