The effects of different aluminum ratios on the preparation of titanium-based alloys via aluminothermic reduction of high-titanium slag were investigated. Titanium-based alloys were prepared by self-propagating aluminothermic reduction using high-titanium slag, aluminum powder, KClO₃, and CaO as raw materials. The thermodynamics and kinetics of the aluminothermic reduction of high-titanium slag were calculated. The results show that high-titanium slag can be used to prepare titanium-based alloys via aluminothermic reduction. The main reaction is the reduction of TiO₂ by Al. The activation energy of the reaction is 274.4 kJ/mol, and the reaction order is 1.04. With the increase in aluminum ratio, the mass fraction of Ti element in the titanium-based alloy gradually decreases, and that of Al element gradually increases. At the same time, there are small amounts of alloying elements such as Fe, Mn, and Si in the titanium-based alloy. Phase analysis shows that under a low aluminum ratio, the main phase is Ti₃Al; under a high aluminum ratio, it is TiAl. The results of chemical composition analysis show that the prepared titanium-based alloy has a composition of 51.6wt% Ti, 40.6wt% Al, 7.6wt% Fe, 3.4wt% Mn, and 1.3wt% Si under the experimental conditions of aluminum ratio as 1.0. The microstructural analysis shows that the prepared titanium alloy consists of a base-phase region, an iron-rich phase region, and a silicon-rich phase region.