Abstract: For the characteristics of iron ore mined-out area, a reasonable choice of geophysical methods, flexibility in the use of geophysical methods is accurate detection of mined-out area the key. According to the changes in the magnetic field before and after the iron ore mining features, combined with pre-geophysical exploration data, geological remote sensing method using ultra-low frequency probe the spatial distribution of mined-out area, depth is a new attempt, combined with other geophysical methods (natural electric field frequency-selective France) can complement each other and India are, better. This paper describes examples of ultra-low frequency geological remote sensing method in detection of iron ore mined-out area of the application results.