The invention relates to a lightning dredger with an insulator function. The dredger comprises a wire hanging head for connecting a high-voltage wire, a main electrode connected with the wire hanging head as well as a multi-arc-extinguishing-chamber system, wherein the main electrode is connected with the multi-arc-extinguishing-chamber system through a main gap, the multi-arc-extinguishing-chamber system comprises a plurality of single-arc-extinguishing-chamber systems connected in series, and each single-arc-extinguishing-chamber system comprises two cylindrical electrodes and a single gap between the two cylindrical electrodes; the main electrode, the main gap and the multi-arc-extinguishing-chamber system are fixed on a support; the main electrode, the main gap, the multi-arc-extinguish-chamber system and the support are covered with an insulation jacket. The lightning dredger combines the thought of dredging type lightning prevention and blocking type lightning prevention, cannot cause a relay protection device to act to trip while discharging the lightning current, is made of common and cheap materials and solves an important problem in whole installation of a lightning arrester.