Abstract: Chemical compositions in leaves of Populus xeuramericana cv 214 and P.deltoides cv Harvard ex 63/51 have been studied.The results show that the chemical compositions of leaves abovementioned two species of popler are not different in the same growing period.Its content all are of much protain,amino acids and rich inorganic elements.But the compositions are different in different seasonal leaves gathered.The content of protainand amino acids have bigger change,changes of other compositions are less.The content of protein and amino acid in leaves of abovementioned two species of poplar are close to or higher than some fodder material. So the abovementioned leaves can be used as fodder of livestocks and poultry.