The invention discloses an application of a blue disperse dye composition as blue disperse dye. The composition comprises dye and a dispersant. A ratio of the mass of the dispersant to the mass of the dye is 0.35:1-5.0:1. The dye comprises, by weight, 15-85% of a component B and 15-85% of a component C. The component B is one or more of compounds 2. The component C is one or more of compounds 3. The composition is bright in color and light, extremely good in alkali resistance and good in light fasteness and can be used for strong-base resistant and superstrong-base resistant scouring-dyeing one bath processes or bleaching-dyeing one-bath processes, disperse/active one-emulsion printing processes and alkaline burn-out printing processes.