Abstract: Volvocales, which includes many important groups,such as Chlamydomonas,　is an important group in the evolution of green plants because some scientists think that green plants derived from green flagellates.Molecular phylogeny of Volvocales has been achieved much by using makers such as rDNA ITS,18s DNA,rbcL gene and so on.Results confirm the notion of single common ancestor, and Chlamydomonas reinhardtii alone among all sequenced green unicells is most possible. We survey the advancement of this area based on the knowledge up to date we have and on our own work on phylogentic analyses of Chlamydomonas inferred from rDNA ITS sequences and morphological characters.