The invention provides a support device for a public service advertising board, and relates to the technical field of public service advertising boards. The support device for the public service advertising board comprises a device body, the device body comprises a base, supporting plates, a stretching device and a supporting device, two supporting plates are fixedly connected to the left and right parts of the top of the base, the two supporting plates are fixedly connected through the stretching device, the stretching device comprises a first vertical plate and a second vertical plate, and the left side of the first vertical plate is fixedly connected with the right side of one supporting plate. According to the support device for the public service advertising board, by arranging the stretching device, the first vertical plate, the second vertical plate, a threaded rod, a driving device, a threaded pipe, a first stretchable rod, a first movable plate, a second stretchable rod and asecond movable plate, the positions of the first movable plate and the second movable plate are adjusted, advertising boards of different sizes and specifications can be fixed conveniently, and manualadjustment of workers is not needed.