The utility model discloses a strut mounting and positioning device of an outdoor power distribution device of a thermal power plant, which is formed by the combination of two symmetrical components, wherein each component comprises a horizontal semi-circle ring disc, a semi-circle pipe tile, direction wings, a handle and magnetic ring bars; the horizontal semi-circle ring disc is in a semi-circle ring shape; the semi-circle pipe tile is in a semi-circle cylindrical surface shape; the direction wings are in a shape of isosceles right triangle cut on a rectangle; the lower edges of the direction wings are calibrated scales; the handle is in a U shape, and the cross section is round; the magnetic ring bars are embedded on the side edge of the semi-circle pipe tile, one end of the semi-circle pipe tile is connected with the horizontal semi-circle ring disc; the long edges of the direction wings are connected with the outer wall of the semi-circle pipe tile, and the short edges of the direction wings are connected with the horizontal semi-circle ring disc; two adjacent direction wings are mutually vertical; the handle is connected with the outer wall of the semi-circle pipe tile; and the magnetic ring bars are mutually attracted so that the two components are integrated. The positioning device and the strut are regulated, thus the crossed line of a support steel plate is consistent with the direction wings of the positioning device, and the direction wings and the central crossed line of a base cup opening are overlapped for positioning. The central line deviation is less than or equal to 2mm, and the vertical degree deviation is less than or equal to 3mm.