Abstract: The floral development of the Theaceae species, Camellia semiserrata Chi. was observed under scanning electron microscope (SEM) for the first time up to date. Both perianth were initiated spirally and centripetally; in the species four to five carpel primordial arose from a ring meristem; in the flowering developmental process the carpels in C. semiserrata Chi. developed nearly into syncarpous gynoecium, and the carpels developed into connate stylus. The surface of stigma had a lot of papilla cells, and it was divided into 3-5 clefts. The stamen was divided into two wheels, and the internal stamen primordia all developed on a ring meristem; 15-21 stamen primordia in the inner whorl first arose simultaneously; the outer whorl of stamen primordia was divided into 3-5 layers; the same layer developed simultaneously on a ring meristem; different layers irregularly initiated; in the flowering development process the outer stamen primordia developed nearly into 1/3-1/2 of based connate stamens. The floral development of C. semiserrata Chi. is distinctly different from those of Adinandra latifolia(Theaceae) and Euryodendron excelsun(Ternstroemioideae, Theaceae). This study provides evidence from floral organogenesis about the further study on the phylogeny of Camellia and even of Theaceae.