The utility model discloses an electric power mounting wire tightening device, including base (1), universal wheel (2), stand (3), keyway (4), lower sheave (5), down round pin axle (6), go up round pin axle (7), top sheave (8), bed hedgehopping piece (9), housing (10), slide rail (11), slider (12), go up fastener (13), lead screw (14), hand wheel (15), down fastener (16), fixing base (17), gear (18), revolve wheel (19) and lock tooth spare (20), during the use, the electric wire passes through between lower sheave and the top sheave in proper order, goes up the fastener with down between the fastener, finally is to the gear, and during tight line, the hand wheel sways the gear, and the electric wire is tightened up, and lower sheave and top sheave design are movable type, can be fit for the electric wire of different diameters, and the electric wire is tightened up the back, revolves hand wheel down, and go up the fastener and the fastener is tight with wire card down, locks tooth spare and locks the gear, prevents the slip. The utility model discloses simple, low in production cost rational in infrastructure, simple to operate.