Carbon mineralization technology is considered one of the most direct and effective approaches for CO₂ sequestration and addressing the issue of greenhouse effect. Stainless steel slag, primarily composed of γ-dicalcium silicate (γ-C₂S), possesses significant potential for carbonation due to its composition. In this study, 80% (mass fraction) stainless steel slag and granulated blast furnace slag powder were used as main raw materials to prepare A12 dry density grade foam concrete. The effects of preconditioning time and carbonation time on the compressive strength and carbon fixation ratio of foam concrete were investigated in a carbonation environment of 0.4 MPa and 60 ℃. The results show that the best preconditioning time is 2 d. The compressive strength of foamed concrete with preconditioning 1 and 2 d reaches the peak after carbonization for 3 d. The compressive strength of foamed concrete with preconditioning 2 d is 51.19% higher than that of preconditioning 1 d. When carbonization for 3 d, the carbon fixation ratio of foamed concrete with preconditioning for 1 and 2 d is 9.94% and 12.10%, respectively. In this study, it is of great significance to realize the carbon mineralization process by using industrial solid waste in a simple carbonization environment, which not only consumes a large amount of solid waste, but also stores carbon dioxide.