The invention discloses an aluminum-scandium intermediate alloy, which comprises the following components in percentage by weight: 2.0 to 4.0% of Sc, not more than 0.05% of C, not more than 0.03% of Cu, not more than 0.08% of Fe, not more than 0.005% of Si, and the balance being Al. The invention also discloses a preparation method of the aluminum-scandium intermediate alloy. The preparation method comprises the following steps: preparing nano scandium powder with a diameter of 50-100 nm, high purity aluminum ingots, high purity aluminum foils, and high purity argon according to weight percentage; at first, adding high purity aluminum ingots into a graphite crucible, heating the graphite crucible to a temperature of 950 DEG C by a resistance furnace so as to melt aluminum ingots; tightly wrapping nano scandium powder by high purity aluminum foils, then pressing aluminum foils into liquid aluminum melt, keeping the aluminum foils in the aluminum melt for 10 minutes; uniformly stirring the melt for 5 to 10 minutes by an electromagnetic stirring technology so as to evenly distribute scandium; pouring qualified aluminum-scandium alloy melt into a preheated water-cooling iron mould, carrying out casting at a temperature of 800 DEG C, and cooling to the room temperature after casting. The preparation method has the advantages that segregation is overcome, the scandium loss is little,the recovery rate is high, compared with a conventional doping method, the cost is lower, and the economic benefit is good.