This　paper　develops　a　state　transition　analytical　model　to　explore　the　endogenous　dynamic　law　of　supply　chain　and　interaction　of　its　endogenous　variables.　By　developing　a　differential　equation　system　for　this　model　and　applying　the　physical　phase　diagram,　we　attest　that　endogenous　factors　as　well　as　the　spontaneous　dynamic　law　in　a　supply　chain　will　determine　its　evolution　trajectory,　to　which　the　effect　of　initiatives　and　activeness　of　supply　chain　members　is　also　not　ignorable.　©　2013　IEEE.