Since Linnaeus established the genus Populus， many taxonomic studies have been carried out about it and some taxonomic systems have been proposed， while the taxonomy of Populus is still in the stage of traditional morphological classification around the world. Although the taxonomic hierarchy of ‘genus-section-species’ is adopted in many countries， in which has Populus plant distributed， there are great differences in the classification of species， subspecies and varieties. The taxonomists of China and the United States are the representatives of splitter and lumper respectively， and there is a huge gap in poplar classification between them， but each has advantages and disadvantages. Even in China， there are still many problems to be solved. The existing phylogenetic studies about the genus Populus provide useful information to taxonomic revision， but the actual contribution is small yet. The ultimate aim on poplar classification is to establish a unified taxonomic system based on phylogeny in the world. It requires a comprehensive classification based on both population and the concepts of integrated species， which integrates morphology， ecology， biogeography， genomic bioinformatics and evolutionary biology.