The invention discloses a rotary table for deepwater drilling rig. The rotary table for deepwater drilling rig includes a base assembly which is installed an upper cover plate on the upper face. A turntable is arranged in the base assembly and the center through hole of the upper cover plate. The bushing way of the turntable utilizes the transition structure four times, which is to have a plurality of radial corresponding semicircular grooves respectively between the inner edge of the through hole of the turntable and the outer edge of the outer ring master bushing, the inner edge of the outer ring master bushing and the outer edge of the circle master bushing, the inner edge of the inner master bushing and the outer edge of the bushing. The two radial corresponding semicircular grooves in each group round into a pin hole, forming three ring pin holes from the outside to the inside. A torque pin is arranged at the pin hole which the two radial corresponding semicircular grooves in each group round. Between the inner edge of the circle master bushing and the outer edge of the inner master bushing, the invention utilizes the groove coupling structure to locate and fix. The device of the invention has the advantages of compact structure, reliable operation and good adaptability.