The embodiment of the utility model discloses an adjustable bracket arranged on a vertical shaft opening protective wall. The adjustable bracket comprises a groove-shaped clamping piece (1), a hangingpiece (3), a vertical length adjusting assembly (5), a steering connecting piece (2) and a fastening piece (4), the vertical length adjusting assembly (5) is connected to the groove-shaped clamping piece (1). The hanging piece (3) is detachably connected to the steering connecting piece (2), the steering connecting piece (2) is detachably connected to the vertical length adjusting assembly (5), and the vertical length adjusting assembly (5) comprises a first connecting rod (51) and a second connecting rod (52) connected to the top of the first connecting rod (51). The height of the support isadjusted through the vertical length adjusting assembly, the working conditions of different vertical shafts are met, the steel wire or steel ruler hanging device can be hung by only one person, theposition of the steel wire or steel ruler is adjusted through repeated measurement, and the labor cost and the material cost are saved.