The invention relates to a plasma drilling bit in the field of drilling bit tools. The technical scheme adopted by the invention is that a fluid passageway and an electrode through hole which respectively and axially communicated are preformed in a bit body; a high-voltage positive electrode and insulators are fixedly connected with the interior of the electrode through hole; the bottom part of the bit body is fixedly connected with an annular ground electrode; the bottom part of the high-voltage positive electrode is provided with a high-voltage panel mounting electrode; an annular interelectrode gap is reserved between the high-voltage panel mounting electrode and the annular ground electrode. The bit penetrates a plasma channel formed in front of to-be-drilled rock under the high-voltage pulse liquid phase microdischarge action to crush the rock, and does not need to be contacted with the surface of the rock, and mechanical lapping is not needed. The plasma drilling bit disclosed by the invention has the advantages that the abrasion of the bit can be reduced, the rate of penetration is increased, and the required energy is low; compared with the conventional mechanical rotary bit, the plasma drilling bit is low in cost and high in efficiency, and can also be applied to industry of mining and the like.