The invention discloses a method for preparing spinnable mesophase pitch through coal pitch hydrocatalysis-hydrogen supply treatment. The method comprises the following steps: (1) adding aids into coal pitch, promoting primary inorganic mineral to form a dispersed catalyst in situ under the high-temperature hydrogen condition, performing hydrocatalysis treatment on the coal pitch, performing reduced pressure distillation after reaction to remove a fraction with low boiling point to obtain primary hydrogenated pitch; (2) adding a hydrogen supply agent into the primary hydrogenated pitch, performing hydrocatalysis-hydrogen supply cooperative treatment under the high-temperature hydrogen condition, and performing reduced pressure distillation to remove a fraction with low boiling point to obtain secondary hydrogenated pitch; (3) removing a quinoline insoluble substance from the secondary hydrogenated pitch to obtain refined hydrogenated pitch; and (4) performing thermal polymerization reaction on the refined hydrogenated pitch to obtain the spinnable mesophase pitch. Through hydrocatalysis-hydrogen supply combined treatment, formation and transformation of the mesophase pitch can be effectively regulated and controlled; and the obtained spinnable mesophase pitch has excellent quality, moderate softening point and high mesophase content and can be applied to preparation of high-performance pitch-based carbon fiber.