The present invention relates to a panel, especially for a component having a box structure in an airplane airfoil, comprising a surface shaped body and grid-like reinforcement bars protruding from the body on one side of the body, and the body and the grid-like reinforcement bars are integral molded. Since the body and the grid-like reinforcement bars of the panel are integral molded, no additional connecting process is required, so that the disconnection phenomenon as happened between the skin and the stiffener or stringer of the prior art would not occur, and the assembly complexity can be decreased.