Abstract: The obtained ITS(internal transcribed spacer) sequences of five species (Eriocaulon nepalense,E.cinereum,E.alperstre,E.sexangulare and E.oryzetorum) in Eriocaulon by PCR technique were analyzed by PAUP 4.0 10 b software,and the strict consensus tree was constructed using Juncus dregeanus as outgroup in this study.The results showed that the ranges of ITS1 and ITS2 size of the tested five species were 171-306 bp and 184-288 bp,respectively,and the ranges of G+C content of ITS1 and ITS2 were about 38.24%-55.04% and 36.46%-57.02%,respectively,indicating that the ITS sequences of Eriocaulon plants were not completely identical.It was found that there were 174 constant characters and 564 varied characters (including 276 information characters) in the total 738 characters of the tested ITS sequences by the Clustal X(1.81) multiple sequence alignment.In addition,there were two branches in the constructed phylogenetical tree,in which E.nepalense,E.oryzetorum,E.alpestre and E.cinereum were grouped as one branch,while E.sexangulare presented an independent branch,and the above two branches mentioned with outgroup Juncus dregeanus were finally grouped with 100% of bootstrap.The obtained results provide an important basis for the further study on the confirmation of phylogenetic position of Eriocaulaceae and Eriocaulon.