Medium-titanium blast furnace slag (MTS) is a major solid waste in the smelting process of vanadium and titanium magnetite. The moderate TiO 2 content in MTS makes it unsuitable for titanium extraction and difficult to be used as cement mixing material in large quantities. In this study, the molten MTS was utilized to prepare micro-crystal stones by a "one-step" cooling method, and the TiO 2 in the slag was used as a nucleating agent. The effects of the cooling process and MTS utilization on the slag structure, crystallization characteristics, and physical properties of the micro-crystal stones were investigated. The results show that when the utilization of MTS is 100 wt%, the main crystalline phase of the microcrystal stones is akermanite, the compressive strength and micro-hardness are 142.5 MPa and 696.9 kgf⋅mm −2 . When the utilization of MTS is 90 wt%, the main phases of microcrystalline stone are augite and akermanite, and the compressive strength rises to 194.8 MPa. Hence, through proper cooling control, the preparation of micro-crystal stones with good performance by using molten MTS as raw material will have considerable economic value.