In order to illustrate the flowering characteristics and sexual reproduction of the rare and endangered plant Sinojackia microcarpa， the morphological characteristics of flower， flowering dynamics， pollen ovule ratio（P/O）， stigma receptivity， pollen viability， bagging experiment， pollinator insects and pollinator frequency were investigated respectively. The results showed that： （1）the hybridization index（OCI） was four， the flowering period was 5-7 d， and the flowering period of the population lasted 20 d. Pollen to ovule ratio was 4 093.21±498.56. The pollen viability was the highest on the third day after flowering（76.21%）， but the lowest on the seventh day after flowering（18.37%）. The most suitable period of stigmas was on the second day after flowering. （2）The bagging result showed that： there were some self-incompatibility and no apomictic reproduction in S. microcarpa. Pollinators were necessary for the reproductive process of S. microcarpa， and cross-pollination could improve the rate of fruit and seed setting. There were seven species， five families and three orders in the visiting insects of S. microcarpa. The main pollinators were Xylocopa appendiculata， Bombus sp.，Vespa sp.，Apis cerana，Episyrphus balteatus. The average pollinator frequency of Bombus sp. was （8.67±0.21） times per hour. Further research on the biological characteristics of flowering and breeding system of this species would be helpful to further explore the mechanism of its endangerment， and provided theoretical basis and reference for future studies on rare and endangered plants.
