The invention discloses a preparation process of an aluminum-based boron carbide neutron absorbing material. The preparation process is characterized by comprising the following steps of (1) aluminumpowder preprocessing, (2) B4C powder preprocessing, (3) ball-milling mixing, (4) biscuit pressing and (5) hot-pressed sintering. The two types of powder are preprocessed before being mixed by adoptionof a dual preprocessing process, the dryness of the powder is improved through the process of two drying and one ball milling, subsequence procedures are implemented advantageously, the density of the final neutron absorbing material product can be improved, and interface bonding between the B4C powder and the aluminum powder is further improved; and uniform powder mixing and composition stabilization are ensured, and the effect that the product is stable in performance is ensured.