Abstract: In order to study the gas deposition and diffusion in environment, the preparation process of radioactive gas ¹²⁷Xe as a new gas tracer is investigated. The ordinary xenon was filled in glass tubes and irradiated for 96 h in nuclear reactor. The irradiation products was transported into a special source box filled with activated charcoal at liquid nitrogen temperature. When the equilibrium distribution of gas Xe in the source box is achieved, the γ-spectrum was continuously acquired. The experiment result shows that the present ¹²⁷Xe preparation process is feasible.