Abstract: The traditional smelting process of vanadium-titanium uses the concentrate with high iron grade and low impurity content as raw materials, but a large amount of titanium in the raw ore is lost in the tailings during the mineral process. If the raw ore is directly used as raw materials for direct reduction-magnetic separation without mineral process, the titanium-containing magnetic separation slags can be obtained, and the recovery of titanium can be improved. However, the magnetic separation slags will contain a large amount of silicate gangue, so it needs further treatment. In this study, the ammonium sulfate roasting method is used to extract titanium from the magnetic separation slags. The results shows that the leaching rates of Ti, Fe, Al, and Mg in magnetic separation slag are 80.56%, 50.36%, 39.83%, and 43.09%, respectively at the conditions of roasting temperature 410 ℃, roasting time of 1 h, ammonium sulfate-slag ratio of 3, 5% H₂SO₄ as leaching agent, liquid-solid ratio of 5, leaching temperature 50 ℃, leaching time of 1 h. Besides, the reaction mechanism was analyzed by XRD and SEM. Compared with the traditional process, this process can utilize the titanium in the raw ore more effectively, and has the advantages of a short process and low energy consumption, which provides a new idea for the utilization of vanadium-titanium magnetite.