Abstract: Under the context of the elevated greenhouse gases, how to reduce carbon emissions and increase carbon absorption is the focus of current research on climate change. Based on data of Chinese crude steel production from 1963 to 2016 and greenhouse gas inventory method, we established steel slag carbon sequestration calculation method. The steel slag carbon sequestration from 1963 to 2016 was estimated and the uncertainty analysis was made. The results showed that annual carbon sink of steel slag in China increased from 3.75×10³ t C in 1963 to 1359.32×10³ t C in 2016. The steel slag accumulative carbon sink was 15×10⁶ t C, with about ±30.4% total uncertainty during 1963-2016. The annual carbon sink of steel slag was composed of carbon sink of the current year steel slag and the previous years. Due to the dense structure and low carbonation rate of steel slag, the carbon sink of the current year was small, accounting for 37% of the total, while that of the previous years were relatively large, accounting for 63% of the total. Although annual carbon sink of steel slag was small, the long-term accumulative carbon sink for steel slag was very considerable, which could not be ignored. Future research should refine carbonation rate of steel slag under diffe-rent environmental conditions to reduce steel slag carbon accounting uncertainty, promote the deve-lopment of carbon capture and storage (CCS) technology with steel slag as raw material to increase effective carbon sequestration, which would provide scientific support for China’s international negotiations on climate change.