The paper studied the preparation of Al-Sc alloy by molten salt electrolysis. LiF-ScF3-ScCl3 as the electrolyte, Sc2O3 as raw material, liquid Al as cathode and graphite as anode. The process condition of preparating Al-Sc alloy includes the influence of current density, electrolysis time, temperature of electrolysis, Back EMF, content of Sc in alloy and current efficiency.The content of Sc in alloy prepared by this method has reached to the maximum of 3.437%. The components of alloys showed by SEM were uniform, it is applicable for commercial purposes. Preparation of Al-Sc alloys with scandium oxide as raw materials, it not only reduce environment pollution, but also decease the cost of production. It is reported in many documents, preparing aluminum base alloy by the method of molten salt electrolysis[1-3], people could make many alloys such as Al-Ce、Al-La、Al-RE、Al-Ti、Al-Si-Ti in the aluminum cell, also the method to prepare some rare earth alloys such as Al-Sr、Nd-Fe、La-Ni was reported[4,5]. Use the method of electrolysis to produce some aluminum base alloy with high-melting-point , difficult to restore , high-priced element is a good method because it is technological process is brief, economy is rational, the technology is feasible, this viewpoint is broadly approved in the world. It isn’t necessary to use high-priced Sc as raw material in preparing Al-Sc alloy with molten salt electrolysis, it could control the Sc amounts in the alloy through the different current efficiency and electrolysis time, production in this method could be continuous or semi-continuous, so it is easy to be automatic controlled. A new molten salt system is used in this paper, we use molten salt electrolysis to produce Al-Sc alloy, take scandium oxide as raw material, through the study of the effect of the current intensity，electrolysis time and the electrolysis temperature , Back EMF and cell voltage, the final production Al-Sc alloy contains Sc 2~6%.