The invention belongs to the technical field of dyeing of textile fiber and in particular relates to dye for superfine polyester fiber. The dye is prepared from the following raw materials in parts by weight: 60-70 parts of natural mineral dye, 30-40 parts of sulfur dyestuff, 8-15 parts of dispersing and leveling agents and 2-7 parts of a pH regulator. Compared with the prior art, the invention has the advantages that the natural mineral dye and the sulfur dyestuff are combined and treated by the dispersing and leveling agents, so that the advantages such as high affinity of the sulfur dyestuffs on fiber and the capacities of improving light fastness and wear resistance are remained; because the superfine polyester fiber is large in specific surface area, the saturated adsorption capacity of the dye treated by the dispersing and leveling agents on the fiber is improved, so that the dye can be rapidly adsorbed onto the fiber, and the bonding strength is improved; therefore, the dyeing quality is improved, and the usage of the dyes is reduced.