Although radon gas survey has been widely used in various fields, the method seems to be rarely employed in the prospecting for nonferrous deposits. To expand the application field of radon gas survey and to provide the prospecting for concealed nonferrous deposits with a new means, the authors made a test in the Limu Sn, Nb, Ta ore deposit of Guangxi by using the RAD7 type electronic radon measurement instrument made in the USA and, as a result, not only found distinct radon gas anomalies in soil over the Sangehuangniu and Shuiximiao Sn, Nb, Ta ore bodies that are well consistent with the concealed Sn, Nb, Ta ore bodies but also obtained good ore-prospecting results during the drilling inspection on the outskirts of the ore district. All these achievements provide an effective exploration method for the outskirt prospecting work and the expansion of ore reserves.