The invention discloses a clamping roller type fan-shaped triple segment of a square billet continuous casting machine. The segment comprises a supporting frame which extends downwards in an arc shape, and a plurality of clamping rollers which are arranged at intervals from top to bottom are arranged on the upper surface of the supporting frame; each clamping roller is provided with a roller frame, an upper roller body and a lower roller body, wherein the roller frames are vertically arranged on the upper surface of the supporting frame, the lower roller bodies are arranged at the ends, closeto the supporting frame, of the roller frames, and the upper roller bodies are arranged at the other ends, far away from the supporting frame, of the roller frames; and arc-shaped billet shape controlregions used for controlling the arc-shaped billet shape of a square billet are formed between the upper roller bodies and the lower roller bodies, and the lower roller bodies of the clamping rollersare located on the outer arc surfaces of the arc-shaped billet shape control regions, and the upper roller bodies of the clamping rollers are located on the inner arc surfaces of the arc-shaped billet shape control regions. When a casting billet passes through the regions, the wide-surface billet shape of the casting billet is effectively controlled through matching of the upper roller bodies andthe lower roller bodies, so that the problem of bulging of the wide surface of the casting billet is effectively solved, and the phenomenon that the casting billet is scrapped due to bulging is avoided.