The invention relates to a preparation method of solvent-based nano-carbon black paste. The solvent-based nano-carbon black paste comprises the following basic formation: 6-20% of CAB (cellulose acetate butyrate) resin, 3-15% of wetting dispersant, 6-25% of carbon black pigment and 65-80% of solvent; and the grain diameter D50 of the solvent-based nano-carbon black paste is controlled to be 40-150nm. The nano-carbon black paste has the characteristics of good storage stability, high coloring capability, high transparency, good compatibility and the like, can substitute metal complex dyes, is widely used as a surface coating colorant for packaging materials for children toys, furniture, leather and cloth products, plastic products, metal products, metal coils, aluminum foils and plating films, cigarette packets, candies, food, paper boards and the like, and can be also used as a transparent colorant for gold-stamped films, glass products, high-grade metal baking paint, plastic baking paint and UV (ultraviolet) vacuum coating paint, as well as a colorant for printing ink, jetting ink and the like.