【Objective】Species richness and diversity of understory plants of different types in urban forests of Guangzhou were studied, with an aim to provide the scientific basis for close-to-nature management of plantation and biodiversity conservation.【Method】Plots were set up to survey the stand structure in different types of urban forests of Guangzhou from September to October in 2012. Understory species richness, diversity and evenness index were used to study the species diversity of different types of urban forests.【Result and conclusion】The results showed that the understory species were the richest in natural forests(71 species), which belonged to 46 families and 60 genera, followed by those of plantation (31 species), which belonged to 25 families and 31 genera. The understory species of plantation in rehabilitation were relatively few (31 species), which belonged to 17 families and 30 genera. Diversity comparisons among different types of urban forests showed that the species diversity of natural forests was higher than that of the plantation. The community and the forest landscape were better as well. Therefore construction of plantation of urban forests in Guangzhou with close-to-nature forestry management ideas is of significant implication.