Southeastern Asia includes four of 25 hotspots of global biodiversity. It is estimated that there are approximately 50000 plant species, one sixth of the world plant species diversity. In order to understand and conserve the rich biodiversity in this region, Southeast Asia Biodiversity Research institute, Chinese Academy of Sciences (CAS-SEABRI), was established in Nay Pyi Taw, Myamar, in August, 2015. This special issue provisionally entitled “Plant diversity of Southeastern Asia” will amount to a total of approximately ten to twelve articles about recent discoveries resulting from botanical surveys carried out by researches of CAS-SEABRI in Southeast Asia.