The invention relates to a full-automatic steel wire cutting mechanism. The full-automatic steel wire cutting mechanism comprises a mounting frame; a unwinding cylinder and a conveying cylinder, matched with each other, are arranged on the mounting frame; the conveying cylinder is connected to a conveying motor through a transmission part; the mounting frame is provided with a straightening conveying groove in butt joint with the matching part of the unwinding cylinder and the conveying cylinder for realizing straightening of steel wires; a cutting device perpendicular to the straightening conveying groove is arranged at the tail end of the straightening conveying groove; and a receiving groove on the same one straight line with the straightening conveying groove is arranged on the other side of the cutting device. The full-automatic steel wire cutting mechanism realizes automatic unwinding of steel wire coils through the conveying cylinder, realizes straightening and conveying through the straightening conveying groove, collects the cut steel wires through the receiving groove to prevent natural falling, realizes automatic length fixation of the steel wires through the rotating number of the conveying cylinder, realizes automatic length-fixed cutting, and greatly improves the cutting efficiency.