Objective:　To　analyze　the　constituent　proteins　in　donkey　hide,　the　key　ingredient　for　Ejiao,　an　important　traditional　Chinese　medicine　for　the　blood-related　conditions,　in　hope　to　eventually　decipher　the　biochemical　mechanism　behind　Ejiao＇s　prominent　medicinal　efficacy.　Method:　Two　methods　were　employed　to　extract　proteins　in　donkey　skin.　One　used　TriPure　isolation　reagent　to　extract　the　total　proteins　in　donkey　skin.　Another　used　1%　sodium　dodecyl　sulfate　(SDS)　to　heat　the　sample　at　100　t　overnight.　And　then　sodium　dodecyl　sulfate　polyacrylamide　gel　electrophoresis　(SDS-PAGE)　and　capillary　HPLC　were　used　to　analyze　the　component　of　proteins.　Result:　There　are　not　only　collagen　α1　(I)　and　collagen　α2　(I),　but　also　serum　albumin　in　donkey　skin.　The　content　is　over　25%　in　total　proteins　with　the　method　of　TriPure　isolation　reagent.　The　content　of　donkey　serum　albumin　is　up　to　20%　with　the　method　of　1%　SDS　healing.　And　two　bands,　molecular　weight　are　nearly　200　kDa,　were　found　on　7.5%　SDS-PAGE.　Extracted　these　proteins　to　analyze　with　capillary　HPLC,　they　were　found　to　be　the　complex　products　of　collagen　and　serum　albumin　of　donkey.　Conclusion:　Donkey　serum　albumin　is　a　main　protein　component　in　the　hide,　which　is　a　clue　to　expose　the　effect　of　Ejiao　on　blood.