This paper describes in brief the principle and field work methods of the FD-3017RaA radon measuring instrument. An analysis of ore-bearing profiles in different kinds of typical ore deposits shows that, over the fault shatter zone, the major peak of the radon anomaly reflects the surface exposure location of the structural shatter zone. It is thus concluded that the application of radon measurement to the prospecting for concealed fractures is very effective, and that radon measurement can be especially used as an auxiliary means in search for concealed ore deposits closely related to fracture structures such as faults, joints and cleavages.