The invention provides a rotary mechanism with a mechanical limiting device, which relates to one rotary mechanism and aims to solve the problems that a rotary angle detection device in an existing rotary mechanism is complicated in structure and limited in detection ranged. According to the rotary mechanism with the mechanical limiting device, an output shaft of a rotary body is rotatably arranged on a rotary body base; an output flange of the rotary mechanism is arranged on the output shaft of the rotary body by a bolt; a mechanical limiting device base is arranged on the rotary body base; a mechanical limiting swinging shaft is arranged on the mechanical limiting device base; a mechanical limiting swinging rod is arranged on the mechanical limiting swinging shaft; a pre-tightening tension spring is vertically arranged on the mechanical limiting device base and the mechanical limiting swinging shaft; the mechanical limiting swinging shaft is fixedly arranged on the output flange of the rotary mechanism; four pieces of magnetic steel are arranged on the mechanical limiting swinging rod symmetrically from left to right; two sets of measuring assemblies are arranged on the two sides of the mechanical limiting device base respectively. The invention is used for the rotary mechanism.