The invention discloses a single-loop cut-off steel tube pole tower adopting a V-shaped combined string. The single-loop cut-off steel tube pole tower comprises a tower body, a top-layer ground wire cross beam, an upper-layer guide wire cross beam, a middle-layer guide wire cross beam and a lower-layer guide wire cross beam, wherein the top-layer ground wire cross beam, from the tower body and back to the cut-off side, is provided with a cross beam with one side perpendicular to a target cut-off line, and provided with a one-sided triangular cross beam towards the cut-off side; cross beams at three sides of the triangular cross beam are arranged in the form of an isosceles triangle; the vertex angle of the triangular cross beam is fixed from the tower body; the bottom side of the triangular cross beam is parallel to the target cut-off line direction; the upper-layer guide wire cross beam is provided with a two-sided cross beam parallel to the target cut-off line from the tower body, and is provided with a one-sided cross beam towards the cut-off side and perpendicular to the target cut-off line; the middle-layer guide wire cross beam is provided with a two-sided cross beam parallel to the target cut-off line from the tower body, and is provided with a two-sided cross beam perpendicular to the target cut-off line from the tower body; and the lower-layer guide wire cross beam is provided with a two-sided cross beam parallel to the target cut-off line from the tower body. The single-loop cut-off steel tube pole tower adopts a base pole tower to realize single-loop cut-off and reduce quantity of newly-built tower rods; and after the line is cut off, double loops arranged in different phase sequences are formed to continuously arrange the line, thereby reducing electric field intensity in a guide wire space, avoiding use of a double-loop branch tower, not changing a guide wire arrangement mode of adjacent pole towers and reducing the possibility of modifying the adjacent towers.