Abstract: Based on the coincidence of the β pulse or internal conversion electron in different energy window as a gate signal with their related γ ray or characteristic X ray, a new method are studied in order to determine simultaneously interested radioxenon in ambient air. The background count with this method is 3～4 orders of magnitude lower than that with normal γ spectrometer method, and the optimal detection limit with a order of mBq/m 3 can be reached.