The invention relates to a fully-automatic glass breaking-off device. The fully-automatic glass breaking-off device comprises a breaking-off mechanism, a scrap guiding mechanism, a glass supporting mechanism and a limiting induction mechanism. According to the fully-automatic glass breaking-off device, a whole sheet of glass can be subjected to edge and sheet breaking-off operation, and thus, theprocess requirements on production of glass of small sheets of certain specifications are met; when one edge of the whole sheet of glass is subjected to vertical downward edge breaking-off action, a single edge breaking-off cylinder is used for providing a downward acting force, output power is stable, a cylinder output speed can be rapidly and conveniently regulated, and the edge breaking-off action is reliable; a proximity switch is adopted as a control element for the edge and sheet breaking-off operation, thus, positions, relative to the whole sheet of glass, of cutter blades can be accurately controlled, the glass is subjected to the edge and sheet breaking-off operation after the cutter blades move to proper positions, and thus, the operability is good while the locating accuracy ishigh; glass scraps generated during the edge and sheet breaking-off operation of the glass are subjected to timely collecting treatment through the scrap guiding mechanism, meanwhile, a glass trolleyis ingenious in structural design, and thus, the operability of pouring of the glass scraps by working personnel is improved.