The invention discloses a deep preparation technology of coal for direct coal liquefacation. Feed coal is selectively crushed and then is sieved with a 0.5 mm particle size to grade; products passing through the sieving are separated through gravity concentration equipment, so as to obtain gravity treated cleaned coal, gravity treated middlings and gravity treated tailings; the gravity treated middlings is ground and fed into size mixing equipment; flotation reagent is added to the size mixing equipment, size mixing is performed, and then products are pumped into flotation equipment to perform separation, so as to obtain flotation cleaned coal and flotation tailings; the flotation cleaned coal is filtered and dried and then mixed with the gravity treated cleaned coal to form rich-vitrinite coal which is served as coal for direct coal liquefacation; and the products of the feed coal not passing through the sieving after crushing and sieving, the gravity treated tailings and the flotation tailings are mixed into rich-inertinite coal which can be served as high-quality steam coal, coal for gasification and the like. The technology is based on coal petrography maceral, adopts the differences in terms of densities and surface natures of different coal petrography maceral, and adopts the method of the combination of gravity concentration and flotation, so as to realize the large-scale separation and enrichment of coal maceral, increase the hydrogen-to-carbon ratio of coal for liquefacation, greatly improve the oil yield of direct liquefacation of coal, and obviously increase the economic benefit of direct liquefacation of coal.