Abstract: Endogenous polyphenol contents in leaves,buds and phloem of different nodes of 3-year-old open pollinated apple seedling trees Malus domestica Borhk. (Jonathan×Golden gelicious) were analyzed by high performance liquid chromatography. Phloridzin was not detected in bud samples from the base to node no.80,However,it appeared abruptly in alarge amount in buds starting from node no.80, little caffeic acid was detectable above node no.80 in the barks and leaves. Myricitrin was not detected in the bark around node no.120, the contents of chlorogenic acid in buds changed significantly.Indicating that node no.80 and no.120 was the physiologically critical point of apple seedlings in phase change.