Abstract: To determine the flower characteristics and sexual breeding system for Fritillaria unibracteata, a combination of field tests and microscopy examination was used to study the flower conformation and pollination biology in order to provide scientific information to assist in plant breeding. This species has a single bisexual flower borne at the stem apex. Occasionally there are two flowers when cultivated for three years from bulbs. The immature bud is green and then turns a darker purple covered with light yellow flecks. The flowering period is from May to June but single flowers bloom only 6-8 days. The bell-shaped flower has six perianth segments in two whorls and six apopetalous stamens within, five of which are tightly circumfused to the pistil and the other independent. The epigynous ovary has three short splits on its hairy chapiter which are secretory. The ovary stands higher than the stamens in the young bud, but becomes shorter in mature, open flowers. The pollen quantity, and vigor is maximal on the first day of flowering and pollen is produced for three days. The pistil stigma in a 1.5 cm long green bud was already receptive. Anther dehiscence coincided with the peak in stigma receptivity but stigma receptivity lasted longer (over 6 days) than pollen production. The flower has over 6000 pollen grains and 160 ovules in single flower, resulting in a pollen to ovule (P/O) ratio of 37.5. The out crossing index (OCI) was 4 according to the flower size and behavior. Pollinators included wind and a few wasps, bees, spiders and other miscellaneous insects. Our results suggest that this species should possess a sexual breeding system with partial self-compatibility, heterogamy, and required pollinators.