The invention belongs to the technical field of metallurgical processes and equipment, and relates to a continuous casting and rolling production line capable of avoiding ferrite rolling mixed crystals and a control method. The invention discloses a continuous casting and rolling production line capable of avoiding ferrite rolling mixed crystals. The continuous casting and rolling production line comprises a continuous casting machine, a roughing rolling unit, an intermediate billet heat preservation device, a finishing rolling unit, an after-rolling cooling device, a high-speed flying shear and a coiling unit which are sequentially arranged along a rolling line. A rolled piece heating device, a descaling device, an accident handling device, an intermediate billet cooling device and the like can be arranged on the production line according to needs. The intermediate billet heat preservation device is arranged in front of a finishing mill group, the temperature of the intermediate billet when reaching an inlet of the intermediate billet heat preservation device is controlled to be below the ferrite phase change temperature, the heating temperature of the intermediate billet heat preservation device is controlled, the intermediate billet is subjected to heat preservation or slow cooling in the device, the austenite-ferrite phase change time is prolonged, and the production efficiency is improved. And phase change is fully carried out, mixed crystals caused by double-phase rolling are avoided, and the structure property uniformity of a ferrite rolled product is improved.