When　steel　slag,　a　by-product　of　steel　making　in　impurity　catching　process,　is　added,　the　forming　process　of　cement　clinker　and　the　major　reactions　in　that　process　are　changed.　Since　there　are　dramatic　differences　between　the　chemical　components　and　mineral　compositions　of　steel　slag　and　that　of　natural　cement　raw　materials,　the　empirical　equation　for　the　calculating　forming　heats　of　cement　clinker　made　of　limestone　and　clay　is　no　longer　applied　for　those　made　of　steel　slag.　In　this　paper,　the　empirical　equation　for　forming　heat　calculation　of　steel　slag　added　cement　clinker　was　promoted,　and　testified　by　acid　dissolution　experiments.　Results　showed　that　the　change　of　raw　materials　had　great　influence　on　the　forming　heat　of　cement　clinker.　When　the　traditional　raw　materials　were　replaced　with　steel　slag,　the　forming　heat　of　cement　clinker　reduced.　Calculating　the　forming　heat　by　our　revised　empirical　equation　can　help　reduce　errors　and　bring　great　convenience　for　the　calculation　and　evaluation　of　heat　efficiency.　This　research　provides　theoretical　underpinning　for　the　study　and　calculation　of　forming　heat　of　steel　slag　added　cement　clinker.　©　(2015)　Trans　Tech　Publications,　Switzerland.