Human　activities　interfere　with　natural　Phosphorus　(P)　cycles　by　introducing　increased　levels　of　P　emissions　to　air,　land,　and　water.　A　supply-side　analysis　of　P　supply　chains　and　associated　P　emissions　can　provide　insights　into　underlying　economic　activities　and　transitions　responsible　for　human-induced　P　emissions.　Taking　the　mainland　China　as　the　case,　this　study　constructs　time-series　physical　input-output　tables　to　describe　P　supply　chains　during　1949-2012.　Subsequently,　it　identifies　critical　products　and　influencing　factors　of　P　supply　chains　enabling　P　emissions　to　the　environment　(including　air,　land,　and　water)　from　the　supply　perspective.　The　results　show　that　phosphate　rock,　an　important　initial　supplier　of　P　from　natural　environment　to　China＇s　P　supply　chain,　was　responsible　for　86%　of　P　emissions　in　2012.　Moreover,　food　crops　and　livestock　are　important　initial　suppliers　of　P　from　soil　to　China＇s　P　supply　chain,　through　cultivation　and　pasturing,　respectively.　From　1949　to　2012,　the　change　in　primary　input　level　was　the　largest　driver　of　P　emission　increments,　followed　by　changes　in　population,　emission　intensity,　and　primary　input　structure.　On　the　contrary,　changes　in　production　structure　reduced　P　emissions.　These　findings　could　support　supply-side　policy　decisions　on　P　emission　control.