Abstract: The activity concentration of ²²²Rn, ²²⁰Rn and their progenies of certain working places and dwellings in Baotou city were measured simultaneously. Based on these results, the equipment factor of ²²²Rn is 0.35 for working places and 0.43 for dwellings, while equipment factor of ²²⁰Rn measured at 20 cm distance from wall is 0.030 for both working places and dwellings. Preliminary results show that the temporal change of ²²⁰Rn equilibrium equivalent concentration is same as ²²²Rn which is high in midnight and low in afternoon, and significant difference between instant and accumulated measure result of ²²²Rn, ²²⁰Rn activity concentration is found, with the factor of 2.1 and 1.7.