Objective To provide basis for identification and utilization of Phytolacca decandra. Methods Anatomic structures of different-aged storing roots, stems and leaves of P. decandra were studied by light microscope and histochemical localization. Results Different-aged vegetative organs have active proteins except the young roots, and the protein used to exist in parenchyma cells. ConclusionProtein content in young stems is the highest and the grain size is bigger than the other organs, and the protein content and grain size in young stems have notable differences from that in the old leaves, young leaves, old stems and roots. No protein has been found in two-year-old storing roots and extra cambium.