The invention provides a continuous beam bridge support prepressing device. The continuous beam bridge support prepressing device comprises a bracket and a longitudinal distribution beam laid on the upper end of a transverse beam, a plurality of finished rolling deformed steel bars embedded in a construction bearing platform and a core-through type hydraulic jack; and the longitudinal distribution beam is welded and fixed to a steel plate reserved at the top end of a pier column; a bailey beam reaction frame is laid on the upper end of the longitudinal distribution beam; the finished rolling deformed steel bars are all fixedly connected with the bracket, and the upper ends of the finished rolling deformed steel bars penetrate through the longitudinal distribution beam and the bailey beam reaction frame in sequence; the core-through type hydraulic jack is arranged on the finished rolling deformed steel bars in a sleeving mode, shape steel reaction beams are arranged between the lower end of the core-through type hydraulic jack and the bailey beam reaction frame, and a reaction upper nut is connected to the upper end of the finished rolling deformed steel bars part of the core-through type hydraulic jack; and a bearing beam is arranged between the reaction upper nut and the core-through type hydraulic jack. The continuous beam bridge support prepressing device omits the manufacturing time and costs of a traditional pre-pressure sand bag, a concrete prefabricated block and a water bag, reduces construction safety risks, is simple in prepressing equipment, and easy to operate.