Abstract: 【Objective】The purpose of this study was to reveal the floristic composition and characteristics of seed plants in limestone areas in Hainan.【Method】Extensive field work, specimens collection and identification were conducted to collect data for the analysis.【Result and conclusion】A total of 1 176 species, 58 varieties and 1 forma belonging to 645 genera and 142 families were recorded. The tropical and subtropical distribution elements, especially tropical Asia ones, were dominant in the limestone flora in Hainan. The tropical and subtropical distribution families accounted for 73.24% of the total and the genera accounted for 87.75%. The proportions of temperate distribution families and genera accounted for 11.97% and 7.29%, respectively. The limestone areas contributed about 27.26% to the total number of species with less than 2% land area of the whole island. However, many genera include only one or very few species. There are 113 single and few species families, accounting for 79.58% of the total families. There are 2 genera endemic to China.