The utility model provides a petroleum-exploration underground exploder, which is applied to petroleum-exploration underground explosive source excitation construction. One end of a shot line is connected with an outlet line of a detonator, and the detonator is arranged in an explosive package. Two leads are parallel to the shot line and fixed on the outer wall of the shot line; the outer surfaces of the two leads are provided with insulation layers; and the lower ends of the two leads are connected with other, and the connecting part of the two leads are positioned in the explosive package. The underground exploder has the effects that through measuring the resistance of the two leads which form a loop on the ground, the depth of the explosive package in the well is measured, so that a reliable basis for monitoring the depth of the explosive package in the well is provided.