Abstract: The secondary phloem structure among three species in Liriodendron (Liriodendron chinensis,L. tulipifera and L. chinensis×tulipifera)was studied. There were obvious differences in terms of length and tissue proportion of phloem fiber, number of sieve plate bar tissue proportion of oil cell and the size of phloem ray. Compared with L. chinensis×tulipifera and L. chinensis, L. tulipifera had longer sievetube element and parenchyma strand. The larger tissue proportion in fiber and oil cell. L. tulipifera was more original while L. chinensis was more evolutionary advanced in terms of compound sieve plate bar number. It suggested that phloem ray parenchyma cell has anticlinal division ability due to the increasing of tangential size of some rays near the outbark in the phloem.