Abstract:In this paper, 5 genera and 8 species of Hydrocharitaceae are recorded. Among them, Blyxa aubertii Rich., B. echinosperma(Clarke) Hook. f and Vallisneria denseserrulata (Makino) Makino are the first to be recorded from Zhejiang Province. As to the horizontal distribution, species of Blyxa Noronha only occur in southeast of Zhejiang, but species of Vallisneria L. are found in wlole province except in the south of Zhejiang. With regard to the vertical distrilutien, lelow 600m of altitude, the number of species and the amount of distribution of Blyxa Noronha tend to increase with the increase of altitude, but the/tend to decrease with the further increase of altitude. The number of species and the amount of distribution of the other genera tend to decrease with the increase of altitude. The distribution patterns of Hydrocharitaceae are chiefly related to the habitats of each genus. The flora of Hydrocharitaceae in Zhejiang is closely related with the subtropical areas of China, especially with its adjacent province.