The invention relates to a flat optical fiber with high-temperature resistance. The flat optical cable is characterized by comprising a sheath, optical fiber, support pieces and reinforcing pieces, wherein the optical fiber is arranged in the middle part of the sheath, the support pieces are arranged on two sides of the optical fiber, and multiple reinforcing pieces are arranged between the optical fiber and the support pieces; a carbamide protection layer is arranged on the outer side of the sheath. The carbamide protection layer is arranged on the outer side of the sheath of the optical fiber, carbamide has very high hydrophilic and water absorbing capacity and can increase the humidity of surroundings of the flat optical fiber, the temperature of the small environment around the opticalfiber is decreased, so that the high-temperature resistance of the optical fiber is improved, and the use range of the optical fiber is expanded. Meanwhile, the carbamide protection layer is low in cost and the production cost can be saved.