Abstract: In this study, the plant diversity of 420 samples from 10 major parks in Haikou was investigated usingthe typical quad and the community characteristics were also analyzed. Results indicated that there were 320 plant species, which belonged to 244 genera and 88 families in Haikou city parks. However, the proportion of native plants was relatively lower than that of exotic plants. The dominant population was so clearly classified, such as Cocos nucifera, Ficus microcarpa 'Golden Leaves' and Zoysia tenuifolia. Herb layers had the highest species abundance, however most of them were wild weeds. The species richness of the tree layer and shrub layer were lower than those of the herb layer. The trend of plant diversity showed that herb layer was the highest, followed by the tree layer and then the shrub layer. But there were differences between the parks. Jinniu park and the People′s parkpossessed the highest diversity. Compared with the belt-shaped park and topic park, the comprehensive park showed a significantly higher plant diversity index in the tree layers and shrub layers (P < 0.05). The results provided reference for applications of landscape plants in tropical coastal cities and plant diversity conservation.