The invention provides a rotary positioning support used during instrument and apparatus maintenance. The rotary positioning support comprises a vertical rod, a first bearing block, a first lead screw, a stretchable rod, a magnifying glass, a bearing block, a bottom frame, an electric cylinder, a supporting frame, a fixing rod, a T-shaped rod and a clamping frame; the first bearing block is installed on the first lead screw through a ball nut pair and is assembled on the back wall of the interior of the vertical rod through a sliding rail, the stretchable rod is arranged at the front end of the first bearing block, the magnifying glass is assembled at the front end of the stretchable rod, and the auxiliary observing function is achieved through the design; and the bottom frame is assembledat the upper end of the electric cylinder, the bearing block is assembled at the upper end of the bottom frame through a sliding rail, the supporting frame is arranged at the upper end of the bearingblock, the clamping frame is installed at the inner end of the supporting frame, the fixing rod is inlaid at the outer end of the clamping frame, the T-shaped rod is assembled at the outer end of thefixing rod and is installed at the outer end of the supporting frame, and height adjustment is achieved through the design. The rotary positioning support is reasonable in structure, instruments andapparatuses can be conveniently overturned, lifting can be adjusted, and observation is facilitated.