The invention relates to a preparation method of an egg white fiber, and belongs to the technical field of textile. The egg white is taken as the raw material, a precursor taking polysulfone as a surface layer and the egg white as a core layer is prepared according to a dry-wet spinning method, and the polysulfone of the surface layer of the precursor is removed to obtain the pure egg white fiber. The main ingredients of the egg white are kept, and the structure of a protein of the egg white is not broken in the spinning process. The source of the raw materials is wide, and the preparation process is simple and environmentally friendly. The prepared pure egg white fiber is non-toxic and harmless, has a good performance of adsorbing heavy metal ions in a water body, and can be used in the fields of sewage treatment.