The　reaction　mechanisms　of　sulfur-containing　compounds　in　heavy　oil　in　supercritical　methanol　were　clarified.　Four　sulfur　model　compounds,　namely　n-hexyl　sulfide,　3-methylthiophene,　diphenyl　sulfide,　and　dibenzyl　sulfide,　were　selected　to　simulate　the　conversion　mechanism　of　the　sulfur　components　in　supercritical　methanol.　The　conversion　rate　of　dibenzyl　sulfide　was　100%　after　1　h　of　reaction　in　supercritical　methanol.　The　desulfurization　rate　was　up　to　97%.　The　sulfur　compounds　in　the　products　were　mainly　tetraphenylthiophenol,　which　provided　a　theoretical　analysis　for　the　increase　in　the　sulfur　content　in　asphaltenes.　In　this　work,　by　studying　the　reaction　path　of　sulfur-containing　compounds　in　supercritical　methanol,　we　found　that　supercritical　methanol　could　not　only　accelerate　the　reaction　process　as　a　reaction　solvent　but　also　play　a　role　in　promoting　the　desulfurization　reaction.