The invention discloses a fabricated cap beam mould. The fabricated cap beam mould comprises a bottom mould body, two side mould bodies and two end mould bodies. The bottom mould body comprises two bent end parts and a middle section horizontal steel mould. Supporting frames are arranged on the outer sides of the two bent ends. A sleeve positioning plate is arranged on the middle section horizontal steel mould. Each side mould body comprises vertical rods and transverse rods. The vertical rods and the transverse rods constitute side mould body supports. Notches are formed in the upper ends of the vertical rods. Split thread rods are inserted into the notches and fixed to the side mould bodies through bolts, and thus the corresponding two side mould bodies are connected. An operation platform and a concrete forming steel plate are arranged on the upper portions of the side mould body supports. A side mould body moving mechanism is arranged in the lower portions of the side mould body supports and comprises a longitudinal moving mechanism body and a transverse moving mechanism body. Production operation is simplified, the mould detaching and closing periods are shortened, the turnover rate and the production efficiency of a formwork is increased, meanwhile, the labor cost is reduced greatly, and the product quality is advantageously guaranteed through the optimized structure.