The acquisitions of green tide floating algae were screened and used into qualitative and quantitative culture experiment. Then ITS sequences analysis was carried out. According to the results of the experiments, neither spores nor gametes production was observed according to the regularly morphological or microscopic observation, as well as mature sporangium and gametangium. But on experimental conditions, algae biomass was increasing, and the biomass increased about 31 times in 30 days. The ITS sequence evolutionary tree shows that QF1 and QF2 were all included in LPP complex clade and had close genetic relationship. This showed they should belong to a same species. But the forms of the two differed from each other. The growth and proliferation of algae were usually incorporated into natural growth which was frond self growing up. As other dominant floating species, the algae in our experiment had plenty of branches. When branches fell off or broke, a new alga formed and began multiplying. This should be considered as autologous nutrition proliferation pattern of green tide algae which belonged to another way of proliferation. This self proliferation of green algae was another important reason of sharp biomass increasing of green tide on suitable condition