The invention provides an overturning supporting mechanism of an automobile cab. A drawing wire and a rear support assembly are added on an original structure, the rear support assembly comprises a pull rod and a control arm, the pull rod is hinged to a rear portal frame of an automobile, the first end of the control arm is fixedly connected with the pull rod through a rotating shaft, the first end of the drawing wire is hinged to a support locking arm, and the second end of the drawing wire is hinged to the second end of the control arm. The overturning supporting mechanism of the automobile cab utilizes the drawing wire to drive the support locking arm to overcome a drawing force of a return spring, and accordingly locking of a supporting mechanism is released. Compared with the prior art, the pullable end of the drawing wire is arranged outside an engine cabin, an operator does not need to stretch hands and other body parts into the engine cabin for locking release, and the operating safety is improved. In addition, the distance from the pullable end of the drawing wire to an original operating handle is also very near, and the operating convenience is increased.