Five uninhabited islands in Lianjiang was researched in detail to plant resources by the methods of surveying typical sampling plots and transect lines. According to field investigation data and literature review, statistical analysis of the species composition of seed plants, distribution area types and ecological types by using floristic geography principle, then compared with the similarity coefficients of genura and geographic composition of the genura of seed plants in different regions, and explored the similarity of vascular plant species among the five uninhabited islands and the relationship with island spatial characteristics. The wild seed plants represented by 190 species, belonging to 165 genera in 64 families. The dominant families were Compositae and Poaceae. It was obvious that the plurimotypic families and larger families in terms of the numbers of genura and species in a dominant position, meanwhile in terms of the numbers of families, dominated by oligotypic families and monotypic families. Herbaceous (55.94%) and shrubs (23.27%) preponderated in the life form, trees and vines were at a disadvantage in terms of number, only accounted for 13.86% and 6.93% respectively. The floristic composition was intricate and varied, and in terms of tropical distribution type, with a high proportion of the family and genus levels, accounted for 90.24% and 68.03% respectively, among them the pan-tropical species accounted for 75.62% and 36.05% respectively, the temperate component only accounted for 9.76% and 31.97% respectively, the R/T values of tropical to temperate family was 9.25 while of genus was 2.13, showing that seed plant flora in the five uninhabited islands were of tropical and sub-tropical types, consistent with the subtropical geography of the islands, transitional from tropical to subtropical. In terms of geographical relationship, compared with the seed flora of four regions from south to north in China, the flora was closely related to six uninhabited islands in Pingtan with similar latitudes, the similarity coefficients of genura was 71.32%. The R/T value of five uninhabited islands in Lianjiang was 2.13, which was lower than that of the uninhabited islands in the nearshore Xiamen (4.23) and the six uninhabited islands in Pingtan (2.58), and higher than that of the five nonresidential coastal islands in Zhejiang (1.11) and the nine uninhabited islands in the Bohai Sea area (0.66). With the increase of latitude, there was a growing tendency on the temperate component at genus-level, while the tropical component was contrary to the former, and the larger the R/T value, the stronger the tropical nature. In terms of flora similarity, the similarities of species between each of the five uninhabited islands in Lianjiang were low, correlation analysis showed that similarity of vascular plant species among different islands was influenced by island edge and habitat diversity. As a whole, the plant species of the seed flora were diverse with a tropical and subtropical transitional nature, ancient plants were abundant, it was consistent with its geographic characteristics of the transition zone between the pan-arctic and palaeotropial flora.