The invention discloses a blue-to-black disperse dye composition which comprises a component A, a component B and a component C, wherein the component A is a mixture of at least one in a formula (I) and at least one in a formula (IIa) and/or a formula (IIb); the component B is a compound of at least one in formulas (III-1) to (III-3); and the component C is a compound of at least one in a formula (IV). The invention further provides a blue-to-black disperse dye product which comprises the blue-to-black disperse dye composition and an assistant. The invention further provides application of the blue-to-black disperse dye product in dyeing of a hydrophobic fiber material. The blue-to-black disperse dye composition has the characteristics of good dispersibility, good stability, high strength and low dyeing dosage. The formulas are as shown in the specification.