Batrachospermales is an order belonging to Florideophceae,Rhodophyta.It distributes all over the world.China and its adjacent regions are the distribution center.The small-subunit rDNA gene (SSU) sequences from species of Batrachospermales and their relative lineages were used to reconstruct the phylogenetic trees by using the PAUP^* 4.0b10 and MrBayes 3.1.2 software,which contained 12 samples collected from China and 28 species abroad obtained from GenBank.The results showed that the SSU region sequence was 1 871 bp with 709 variation sites (38%) and 169 parsimony informative sites (9%).The phylogenetic relationships were inferred using the maximum-likelihood,neighbor-joining,and Bayesian analysis,and three methods produced trees with largely congruent topology.All phylogenetic trees topology got a similar placement of Thoreales,which formed a monophyletic group with high bootstrap support.According to the Bayesian analysis,the conclusion supported that the Thoreales should be classified as a separate order.Three trees all revealed that Batrachospermum gelatinosum is separated from other members of Sect.Batrachospermum and should be classified as a separate Section.The genus Kumanoa should be admitted based on Sect.Contorta and Sect.Hybrida.