Species diversity of Eriocaulaceae in Dong Na Tard Provincial Protected Area, Savannakhet Province, Lao PDR was undertaken in November 2020. Eight taxa are found, one of which was an unknown taxon. They were Eriocaulon cinereum R. Br., E. Echinulatum Mart., E. hamiltonianum Mart., E. infirmum Steud., E. nautiliforme Lecomte, E. nautiliformoides Praj. & J. Parn., E. truncatum Buch.-Ham. ex Mart. var. florensense Z. X. Zhang and Eriocaulonsp. The generic and species descriptions, and a key tothe species are presented.