Abstract: The floral differences among Impatiens L. are so complicated that there are many difficulties in taxonomy of the genus. Seed coat micromorphology characteristics play an important role in providing critical information on systematics. In the present study，the seed coat micromorphology of 24 species of Impatiens from China were observed and compared by scanning electron microscopy（SEM）. The results showed that seed coat ornamentation in this research could be ascribed into 2 types as reticulate（including fine reticulate，thick reticulate，areolate，carinate and striate subtype）and protrusive（including digitiform，clustered and squamalate subtype），in which thick reticulate subtype was described for the first time. And the variety appeared among the species such as the shape and depth of lumina，width of muri，shape of protrusions，and density of derivatives and so on，could be used to identify the species in Impatiens. The systematic and phylogenetic implications of seed coat micromorphology in Impatiens were discussed. And the possible evolutionary route of seed coat ornamentation was conjectured as well，which suggested that reticulate type was ancestral，others were derivative，and the micromorphological features of seeds could be crucial evidence to locate some species in Impatiens systematically in combine with pollen morphology，micromorphological characters of leaf epidermis and molecular data.