The invention discloses a fixing device for an airplane cap-shaped piece. The periphery of the airplane cap-shaped piece is covered with a skin. The fixing device comprises a fixture body, a plurality of protection blocks, a plurality of cap-shaped piece positioning pieces and a plurality of connector positioning pieces, wherein the fixture body is used for supporting the cap-shaped piece covered with the skin, the periphery of the skin is surrounded by the protection blocks which are used for fixing the skin to the fixture body, the cap-shaped piece positioning pieces are fixed to the cap-shaped piece, and the connector positioning pieces are located on the cap-shaped piece. Each cap-shaped piece positioning piece is provided with a first positioning piece body fixed to the skin and a second positioning piece body fixed to the cap-shaped piece. According to the fixing device for the airplane cap-shaped piece, the skin is fixed to the fixture body through the protection blocks, the direction of the cap-shaped piece is fixed through the cap-shaped piece positioning pieces, and the fixing device is simple in structure, easy to use and capable of solving the cementing positioning problem of the cap-shaped piece and the skin.