A racket frame structure includes a main body having an inner side wall and an outer side wall. The inner side wall of the main body having two sides each formed with a plurality of reinforcement ribs. The reinforcement ribs are located at connections of the main strings and the cross strings on the main body. Thus, the main body at the connections of the main strings and the cross strings is strengthened by the reinforcement ribs so as to enhance the strength of the main body, thereby preventing the main body of the frame from being deformed, distorted or broken at the connections of the main strings and the cross strings due to a larger striking force.