Abstract: The height_associated dyamics of isozymes of peroxidase (POX), esterase (EST), cytochrome oxidase (COD) and alcohol dehydrogenase (ADH) in leaves were studied by polyacrylamide gel electrophoresis (PAGE) in 1,4,14_year_old seedlings and 4-year-old grafted plant, which grafted by adult_phase bud of [WTBX]Malus hupenhensis.[WTBZ] The results showed that, the observability of some bands, such as PO X Rf 0.56, 0.60, COD Rf 0.50, EST Rf 0.09, 0.15, 0.75, 0.77, ADH Rf 0.76, were age variable. Some were found only in adult_phase leaves, and others were unique to juvenile-phase leaves. The height from 150 to 200 cm, where adult-or juvenile-associated isozymes disappeared or appeared was the lowest flowering height. 1-year-old seedling displayed patterns that were identical to juvenile zone of seedlings perennial. Grafted plant has essential bands of adult zone of seedlings perennial. The study disclosed that plant height may be one of the most important factors that govern phase change of Malus hupenhensis. The four isozymes could be served as markers to assess characterization of phase change of perential plants.