The utility model relates to a big leap iron tower of single loop belongs to high tension transmission line technical field, is the longer and short big leap iron tower of single loop of a failure interruption time that provides of power off time when the line fault maintenance appearing to current big leap pylon. Including the body of the tower, locate the body of the tower top layer ground wire cross arm, locate the body of the tower upper wire cross arm, locate lower floor's wire cross arm of body of the tower, the both sides cross arm is arranged to top layer ground wire cross arm, upper wire cross arm, lower floor's wire cross arm perpendicular to circuit direction to the side of the body of the tower, and upper and lower direction is unanimous, and top layer ground wire cross arm hangs the ground wire. Upper strata wire cross arm and body of the tower junction fix the strain insulator -string hang one in the looks wire, lower floor wire cross arm both sides are slightly partially do not fixed the strain insulator -string and are hung a limit looks wire, are trefoil formation between the upper conductor. Compare with conventional single loop tower, possess standby line once, can regard as and examine and repair reserve power supply, avoid the power off time longer, the simple symmetry of iron tower structure is favorable to shaft tower the force balance.