The invention discloses a tail-end tool and a method for removing a foreign matter from a high-voltage power transmission line by a robot. The tail-end tool comprises a base, a clamping tail end and a cutting tail end, wherein the clamping tail end comprises two clamping knife rests, two clamping connecting rods, two clamping claws, a clamping sliding block and a driving apparatus; the clamping claws are fixed at the front ends of the two clamping knife rests respectively while the tail ends of the two clamping knife rests are hinged with the clamping sliding block through the clamping connecting rods; the cutting tail end comprises a cutting knife rest, a cutting connecting rod, two cutting blades, a cutting sliding block and a driving apparatus for driving the cutting sliding block, wherein the cutting knife rest is connected with the middle part of the clamping knife rest in a hinging manner through a fixed pin shaft; the two cutting blades are fixed at the front end of the cutting knife rest and at the bottoms of the clamping claws in opposite positions; and the tail end of the cutting knife rest is connected with the cutting sliding block in a hinging manner through the cutting connecting rod. Operational arms on the robot drive the tail-end tool to remove the foreign matter from the high-voltage power transmission line; the cutting way is reliable, and has no damage to the wire; and in addition, the tool can perform secondary smashing on the foreign matter so as to prevent from secondary winding.