So far, four species of Dictyotaceae have already been reported from the Xisha Islands,South China Sea, Zonaria nigrescens Sonder and Lobophora variegate (Lamx.) Womersley reported previously being synonymous with each other. The four species are Dictyota divaricata Lamx, D. friabilis Setchell, Padina australis Hauck and Lobophora variegata (Lamx.) Womersley. In the present paper, 12 species are reported, of which eight species are newly added to the flora of the Xisha, including one new species, namely, Padina xishaensis sp.nov. The other seven species are Dictyopteris repens (Okam. ) Boerg., Dictyota cervicornis Kuetz., D. patens J. Ag, Padina boryana Thivy, P. minor Yamada, P. jonesii Tsuda, Stypopodium zonale (Lamx ) Papenfuss. Among them, D. cervicornis, P. jonesii and S. zonale are recorded for the first time from China. These species are fully described on the basis of our own materials to facilitate better understanding of these seaweeds. The specimens studied including the type specimen are all deposited in the Herbarium of the Institute of Oceanology,Academia Sinica in Qingdao.