The key problem in the highprecision borehole threecomponent magnetic measurement has been

successfully solved by the authors, and the coordinate system conversion error is 820 nT, with the

accuracy 2030 times higher than the accuracies of the existing products. Accordingly, the borehole three

component magnetic measurement can also be used to find such weakly magnetic deposits as nonferrous

metals, precious metals and rare metals, which have intergrowth relationship with magnetic pyrite minerals

and magnetic minerals. This technique is likely to become an effective tool for deep exploration in the

mine. Only through a detailed investigation of the deep part and the two wings can the scientific

evaluation and decisionmaking for mine resources be made so as to find a way out of the critical mine.

This system can be applied to highprecision inclination logging and also be employed to exact measurement

and control of spatial posture of all movement systems.