Erigeron breviscapus (Vaniot.) Hand.-Mazz., is a perennial herb in the Asteraceae family. It is an important plant used for medicine by the Miao people, as an elixir. A field investigation was conducted on the floral syndrome and breeding system of in Kunming, Yunnan Province. The main results are as follows: the capitulum of E. breviscapus is an inflorescence with centripetal development, the outer ligulate florets develop first, followed by the inner florets. The flowering period of the E. breviscapus population lasted about three months. The life span of one inflorescence was usually about 19-25 days. The life span of one floret was approximately 7-10 days. All florets being protandrous, the mature pollen dispersed in the anther canister. On the day of anthesis, the pistil recipient phase started from style elongation and the stigma was bilobed. It follows that the stamen are exserted from the corolla, and the pollen is "pushed" out the anther canister by the stigma. As a result, there is a spatial isolation of corolla, anther canister and stigma within the same floret. In an inflorescence, outer florets are in the female phase (pistil recipient) when anthesis of inner florets takes place. Thus, outer florets have the chance of being pollinated by the inner florets in the same inflorescence. The out-crossing index (OCI) is ≥ 4. According to criteria put forward by Dafni, the reproduction of E. breviscapus can be determined as out-crossing, partially self-compatible, and requiring pollinators during pollination. The pollen-ovule ratio (P/O) is approximately 1373. E. breviscapus reproduction is facultative xenogamy by Cruden’s criterion. When the inflorescences were bagged, there were few fruits produced. Thus, it is concluded that out-crossing is predominant in the breeding system of this species and fruit setting is depended on visiting pollinators. More than 10 species of floral visiting insects were observed on inflorescences of E. breviscapus. The most common floral visitors were species of bees and butterflies. Pollen competition may be the major factor leading to low fruit setting by E. breviscapus in nature. In addition, the male sterile plants were found in a natural condition and are valuable for breeding.