Abstract: A method for selecting a functional antigen-binding protein. The method comprises the step of constructing an expression vector, by means of a phage display technique and/or a cell display technique, using a light chain or a fragment thereof of a reference antigen-binding protein with a known sequence and function, or a heavy chain or a fragment thereof of the reference antigen-binding protein, thereby selecting a functional antigen-binding protein that binds to the same epitope as the reference antigen-binding protein. Further provided is a functional antigen-binding protein obtained by means of the method.