This paper presents new data processing and interpretation methods for the high-precision magnetic data in search for deep-buried minerals in crisis mines. Such means as the three-dimensional visualized inversion based on the numerical integral of 3D bodies, the weak signal identification by the wavelet analysis tools, the equivalent dipole layer method for the fast reduction of magnetic data from an undulated relief to a horizontal plane, and the transformation of to, all fall into this category. The performance of these new methods was illustrated in search for deep-buried minerals in the Daye iron mine, and a magnetite ore body more than 30m thick was discovered by the drilling along No.15 exploration line arranged according to the authors' interpretation in 2005. The application of these new methods shows that the adoption of these new methods is essential in the continued resources exploration for crisis mines.