A hair darkening dye composition, comprises: 2-98 parts by weight of hair dye; 1-99 parts by weight of darkening agent; 2-98 parts by weight of crosslinking agent; 2-98 parts by weight of emulsifier; 2-98 parts by weight of dyeing auxiliaries; and 0.1-40 parts by weight of pH regulator. The darkening agent is selected from one or more of chitin, chitosan, gelatin, silicon oil and resin. The chitin, chitosan and gelatin have a relative molecular weight of less than 2.7×104, and the silicon oil and resin have a refractive index of less than 1.55.