This paper first gives the expression for anomalous magnetic field produ ced by spherical orebody buried in bedrock along the surface peincipal profile under the condition of horizontal cover with the adoption of receiving electrode pure anomaly feed system, then gives calculations for anomalous magnetic fields with different electric conductivities under covers of any thickness, and also makes a systematic analysis of the distribution of anomalies. Finally, it is concluded that in prospecting for blind orebodies at depth under the condition of low-resistance cover, the adoption of receiving electrode magnetic-electric-method can theoretically hold water, whereas the surface feed system will surely be useless.