The invention relates to a method for preparing a non-noble metal catalyst for light fraction conversion of C10<+> heavy aromatics. According to the catalyst disclosed by the invention, elemental nickel and nickel phosphide (Ni2P) serve as an active phase, and a molecular sieve and alumina serve as a carrier. With the adoption of a competition adsorbent, the problem that the alumina in the carrier is reacted with phosphorus to produce aluminum phosphate so as to greatly reduce the reaction activity of the catalyst is solved; with the adoption of a low-boiling-point organic matter with strong reducing property, the nickel phosphide phase production temperature is reduced, the nickel phosphide particle aggregation is reduced, and the catalyst activity is greatly improved; the non-noble metal hydrogenation activity phase is adopted to replace noble metals, so that the catalyst cost is greatly reduced.