The　effect　of　the　cooling　rate　on　the　morphology,　number　density,　and　size　distribution　of　MnS　inclusions　in　a　high　sulfur　steel　was　investigated.　With　the　increase　of　the　cooling　rate　from　15　K/min　to　300　K/min,　the　number　density　of　MnS　inclusions　ranged　from　91　#/mm2　to　192　#/mm2,　and　the　average　size　of　MnS　inclusions　decreased　from　7.4　μm　to　5.3　μm.　A　coupled　model　was　developed　to　predict　the　precipitation　and　growth　of　MnS　inclusions.　The　precipitation　temperature　of　MnS　at　different　cooling　rates　was　approximately　1　823　K,　which　agreed　well　with　experimental　results.　Through　the　high-temperature　confocal　scanning　laser　microscope,　the　precipitation　process　of　MnS　in　a　high　sulfur　steel　during　the　solidification　was　observed.　Inclusions　of　MnS　primarily　precipitated　at　grain　boundaries,　while　the　morphology　of　MnS　before　and　after　solidification　was　influenced　by　the　cooling　rate.　A　higher　cooling　rate　promoted　elongated　MnS　inclusions　precipitated,　and　smaller　MnS　inclusions　were　precipitated　after　solidification.　Conversely,　a　slower　cooling　rate　led　to　the　massive　MnS　inclusions　precipitated　during　solidification,　leading　to　the　formation　of　elongated　MnS　particles.　©　2024　The　Iron　and　Steel　Institute　of　Japan.