An insulating brick was developed and evaluated as a potential recycling Waste Limestone (WL) with Melting Slag (MS). We aimed at analyzing the parameters affecting the insulating brick manufacture to enhance the recyclability of WL. In this study, The thermal conductivity, compressive strength and apparent porosity of prepared brick were measured with the addition of aluminum dross and the molar ratio of the alkali activator. The thermal conductivity, compressive strength and apparent porosity were 0.28 W/mK, 2.41 MPa and 44.72% respectively at a mixing ratio of 9.5 : 0.5wt%, 1.5 M SiO2/Na2O, 3wt% aluminum dross. Thus, it met the standards of insulating fire bricks (KS L 3301).