An anti-falling apparatus used in replacing operation of high-voltage transmission line comprises a pulley block and an insulating dragline (L) through the pulley block, the pulley block comprises a pulley (1) slip-connected with the awaiting replacing line, a pulley (2) slip-connected with the line below the awaiting replacing line, and a pulley (3). The insulating dragline (L) passes through the pulley (1) on the awaiting replacing line and the pulley (3). The anti-falling apparatus used in replacing operation of high-voltage transmission line of the utility model can avoid various accidents caused by falling down in line replacing operation, and avoid obstructing the spanned object when replacing line. Further, the anti-falling apparatus used in replacing operation of high-voltage transmission line of the utility model can avoid direct contact between the insulting dragline and a wire, thereby avoiding the rupture of the insulting dragline caused by the repeating friction between the insulting dragline and the wire. The utility model can reduce operation intensity and improve operation efficiency.