The MAX phase Ti2SC is a potential high-temperature structural material and precursor for titanium extraction by molten salt electrolysis due to its special structure and properties. However, the existing preparation methods all involve the use of high-value Ti powder, TiC powder, and TiS powder, since the synthesis of Ti2SC has always been thought to be through the reaction of TiC and TiS. The preparation of high-purity Ti2SC in a low-cost way is the prerequisite for its large-scale application. In this work, with ilmenite concentrate, pyrite, and graphite spherical tailings as the raw materials, high-purity Ti2SC was successfully prepared via the carbo-sulfidation of ilmenite concentrate. Since it was a new reactant system for preparing Ti2SC, the formation mechanism of Ti2SC in the FeTiO3/FeS2/C system was discussed in detail based on the results of XRD and thermodynamic calculation. A new formation mechanism that Ti3O5, the intermediate product of carbothermal reduction of FeTiO3, was directly reconstructed into Ti2SC in the molten FeS was proposed. Then, the effects of graphite proportion, sintering temperature, and holding time on the purity and morphology of products were determined by the orthogonal experiment. Ti2SC with uniform size and purity of up to 96wt% was obtained from the sample containing 27.4wt% graphite after sintering at 1400℃ for 4 h and subsequent pickling treatment continued based on the results of XRD fine-fitting data and SEM. Furthermore, to reduce the amount of acid used in the purification process, the in-situ physical separation of by-product Fe and Ti2SC was realized under 1700℃ high-temperature sintering by taking advantage of the large density difference between Ti2SC and molten Fe. The amount of acid used for purification was reduced by 72.7% according to the comparison of theoretical and actual acid consumption. The results of this study not only proposed a new pathway to synthesize Ti2SC but also provided valuable references for the industrial production of this MAX phase.