Tree peonies belong to Paeonia L. section Moutan DC., Paeoniaceae. All wild tree peonies are endemic to China, which is also the first domestication place of cultivated tree peonies. A new taxonomic system of Sect. Moutan was proposed by Hong and Pan (Hong D.Y. and Pan K.Y. 1999a. Acta Phytotax. Sin. 37: 351–368; 1999b). In their system eight species, of which three each has two subspecies are recognized. Wild tree peonies are distributed in Henan, Gansu, Shaanxi, Shanxi, Anhui, Hubei, Sichuan, Yunnan and Xizang (Tibet) of China. The most densely populated area is Henan province, where five wild species (subspecies) are found and supposed to be related to the origin of cultivated tree peonies. Since 1990 considerable work on taxonomy of tree peonies has been done by Chinese botanists, which is summarized in this paper. In addition, the nomenclature history of the tree peony species listed in Hong and Pan's (Hong D.Y. and Pan K.Y. 1999a. Acta Phytotax. Sin. 37: 351–368; 1999b) system is reviewed and the information on their geographical distribution and ecological habitats is presented.