The invention discloses a rotary bracket for tunnel blasting excavation construction, and relates to the technical field of tunnel engineering construction. The rotary bracket comprises a bottom plate, walking wheels are rotationally arranged at the bottom of the bottom plate, a supporting frame is fixedly installed on the bottom plate, a stepping motor is fixedly installed on a lifting plate, a worm wheel in matched connection with a worm is connected to the worm, a vertically-arranged steering shaft is coaxially fixed to the worm wheel, and the upper end of the steering shaft is fixed to thecenter of the bottom of a rotating plate. Forward rotation or reverse rotation of a driving shaft is driven through forward rotation and reverse rotation of a forward-reverse rotation motor, therefore, lifting of the lifting plate is achieved to adjust the height position, the rotating plate and an expansion plate for supporting are adjusted in a lifting mode, the angle of the rotating plate is rotationally adjusted through drive of the stepping motor, a tunnel construction worker on the rotating plate can carry out tunnel construction operation in all directions conveniently, the expansion plate can be extended and expanded relative to the rotating plate, the moving work area of the construction worker is expanded, and therefore construction operation is better facilitated.