Abstract: Relationship of external morphology and internal anatomical structure of pistillate and staminate during flower development in protogynous individual of Cyclocarya paliurus was studied by phonological observation and paraffin section. Results showed that period of staminate flower development was divided into three stages: anther and anther wall, microspore and androgamete, corresponding to morphological changes from anthotaxy elongating and the size of floweret increasing, involucres splitting to color of anther turning yellow. Pistillate flower developmental process included pistillate differentiation, development of ovule, megaspore and female gametophyte, and the change of external morphological characteristics during the above periods appeared as floweret initialbody appearing and growing, stigma exposing and elongating，and changing color of dark green. It indicated that external morphology of flower bud development apparently reflected the changes of internal structure, and could serve as indicator for stages of flower bud differentiation. Also, the factors including dichogamous character, the population size of fruiting plants, and the ratio of protandrous and protogynous plants in this population that may affect fruit in C. paliurus were discussed. 