The invention provides an under-shaft electromagnetic communication system and method, and relates to the technical field of underground resource exploration and development. The system comprises an under-shaft tool, a while drilling shaft measuring instrument, a drilling bit, a while drilling measuring system, and a first wireless electromagnetic communication device and a second wireless electromagnetic communication device which are arranged at the two ends of the under-shaft tool; the first and second electromagnetic communication devices both comprise electromagnetic antenna coil structures, wireless transmission unit structures, wireless receiving unit structures and general signal interfaces; the electromagnetic antenna coil structures can generate axial alternate currents by electric antennas in the directions of drilling rods and generate alternate current rings which wind the drilling rods through magnetic antennas; electromagnetic wireless data communication is conducted between the electromagnetic antenna coil structures of the first and second electromagnetic communication devices through electromagnetic signals skipping the under-shaft tool. By means of the system andthe method, short distance data transmission of under-shaft complicated environment suitable for different dielectric properties can be achieved.