In　order　to　reveal　the　physical　essence　of　the　spreading　process　of　reactive　wetting,　a　sort　of　model　of　energy　to　explain　the　driving　force　and　wetting　mechanism　was　presented.　The　reactive　wetting　of　molten　Al　and　Cu-Si　on　graphite　was　studied　by　a　modified　sessile　drop　method　under　a　vacuum,　in　which　the　contact　angles　were　measured　by　ADSA　software.　The　thermodynamic　and　kinetic　processes　of　the　typical　reactive　wetting　were　focused　on,　the　thermodynamic　equations　of　energy　relations　were　derived,　the　interfacial　energy　of　graphite　and　solid-liquid　interfacial　energy　versus　time　at　the　triple　line　were　calculated,　and　the　dynamics　model　of　interface　energy　is　established.　The　presented　dynamics　model　is　verified　by　means　of　experimental　results,　and　it　is　shown　that　solid-liquid　interfacial　energy　decreases　with　time　in　exponential　relationship.　It　provides　a　new　method　for　reference　to　explain　the　process　from　the　angle　of　energy.