In the field where nuclear survey is comparatively extensively applied, many valuable anomalies detected by field radiometric survey are weak or low-value anomalies. For these low-value anomalies, the authors suggest the utiliza tion of high-precision radiometric survey. In order to raise the reliability oi the determination of these low-value anomalies, the paper points out that impor tance should be attached to the measures for raising the precision of field survey (mainly the surface total gamma amount and gamma spectrometry), which include, for example, the selection of proper instruments and time of measurement, and the control and reduction of interference factors in field survey. Besides, the data-processing is the key-link in the interpretation of weak anomalies. The paper describes briefly some currently-used common methods for determining weak radioactive anomalies and the data-processing method in search for nonradioactive elements by means of data from gamma spectrometry. The third part of the paper outlines the application of field radio-metric technique to the prospecting for gold, petroleum, groundwater sources and other important metallic ore resources and to the solution of problems in the aspect of engineering geology.