The invention discloses a modified polyurethane resin emulsion dye ink and an application thereof. The modified polyurethane resin emulsion dye ink comprises the following components based on weight ratio: 0.1-12% of solvent dye and / or water-soluble dye, 13.5-49.8% of polyurethane resin solid content, 0.01-1% of ultraviolet absorber and the balance of solvent, wherein various additives can be added in the dye ink. The dye ink disclosed in the invention can be used in the fields such as jet ink, cipher paint ink, textile printing ink, aqueous printing ink, fountain pen word ink, rolling maker ink, coating, leather finishing agent, surface finishing and the like, and has the advantages of good storage stability, excellent water resistance, chemical resistance and light resistance, favorable mechanical performance, high brightness, high and low temperature resistance, ageing resistance, good color reducibility and transparency, easily-obtained raw materials, simple manufacture, easy detection, low cost and wide market application prospect.