This is the second part of a series of papers dealing with the marine blue-green algae of the Xisha Islands. A total of 16 species of the marine Oscillatoriaceae are deseribed. They belong to 6 genera and are all recorded for the first time from the Xisha Islands. With the exception of Oscillatoria laetevirens Crouan, Lyngbya nordgaardii Wille and Hydrocoleum cantharidosmum (Montagne) Gomont, which have been recorded from Qingdao, Yantai of Shandong Province and Xiamen(Amoy)of Fujian Province, the other 13 species, namely, Spirulina tenerrima Kuetzing, Oscillatoria brevis Kuetzing, O. subuliformis Kuetzing, O. chalybea Mertens, O. Bonnemaisonii Crouan, O. nigro-viridis Thwaites, O. Corallinae (Kuetzing)Gomont, Phormidium penicillatum Gomont, Lyngbya Kuetzingii Sehmidle, L. infixa Fremy, L, baculum Gomont, L. semiplena (C. Agardh)J. Agardh, and Schizothrix Lacustris A. Braun are recorded for the Chinese marine flora for the first time. The materials for study are chiefly based on the collections made by the Institute of Oceanology, Academia Sinica during 1975-1976.