Calcium element can effectively be leached out and carbon dioxide can be sequestered on the spot to prepare commercial calcium carbonate through leaching of steel slag by ammonium chloride. Due to the decrease of CaO content in steel slag leached by ammonium, there is no need to use a lot of modification agent to reduce and extract iron and prepare glass-ceramics. Therefore, thermodynamic calculation was introduced to explore the feasibility of extracting iron from ammonium leaching steel slag and preparing glass-ceramics. The preliminary results shows that for the mixture of steel slag leached by ammonium chloride and 40wt% SiO2, the reduction rate of iron is as high as 98.47%, and the main phases of reducing residues is diopside; the main crystal phase of glass ceramics is diopside mixed up with some calcium feldspar by nucleation for 1 h at 800 ℃ and crystallization for 1 h at 960 ℃; and the crystallization activation energy of base glass is 597.4 kJ/mol, and the crystal growth indexes are all less than three, indicating surface crystallization.