Based on the ability of VLF electromagnetic waves passing through the stratum, the study is made on the impact of the earth to signals to evaluate the relationship between the frequency, power and signal passing ability, discuss the realization principles of signal localization in signal source, antenna, signal processing and filtering as well as the key technologies, select a reasonable way and carrier mechanism for underground-surface communication, build a simplified magnetic dipole sub-localization model to complete the orientation and depth determination. This paper summarizes the key programs of very low frequency electromagnetic waves localization technology to provide a new communication technology for in-hole signal transmission in drilling field, such as CBM horizontal well, horizontal butted hole, pilot hole of directional drilling and mine rescue.