Abstract: In the process of measuring the moisture of some bulk materials containing those large thermal neutron absorption cross-section elements such as boron, cadmium, samarium, europium, gadolinium etc, most of the thermal neutron will be absorbed by these elememts. Therefore the ordinary method of indicating the material moisture by thermal neutron density will be confronted with difficulties. On the basis of theory and a great deal of experiment and research, a wide energy range neutron receptor is selected to extend the application of the ordinary neutron moisture method; for example, the measuring limit of rare earth contents is raised from 10~(-7)% to 1—2%. The feasibility of determinating the earth minerals containing 30—60% rare earths by neutron method is under study.