Abstract: The diversity of seed plant is rich in the flood plain of Mid-Yellow River, including 84 families, 358 genera and 818 species. There are 11 families, making up 57.26% of the total genera and 62.67% of the total species, which form the basic frame of the composition in this area. The dominant families of flora composition of the vegetation are Compositae (101 species), Cramineae (77 species), Cyperaceae (62 species) and Leguminosae (51 species). In composition of the floristic geographical elements of the genera and species, the temperate elements take dominant position. But it represents distinctiveness between genus level and species level. Although it's an unmarkble characteristic, the tropic genera take the advantage in this flora in contrast to Huabei one. In addition, such endemic to China phenomenon at species level is most marked to that at genera level.