A probe for a trenchless guide instrument includes an antenna, a control circuit board and at least one battery supplies power to the control circuit board; one battery is disposed inside the battery region; the control circuit board is disposed inside the electronic region; a first insulating pipe is disposed inside the antenna and outside the battery, the antenna further includes a magnetic core, and a coil winds around the magnetic cores and one end of the coil is connected to the control circuit board; the magnetic core further includes magnetic core units, each magnetic core unit is made from magnetic material, the magnetic core units are positioned on a peripheral surface of the first insulating pipe, and are insulated from each other.