The investigation and conservation project of plant biodiversity in the submersion district and the immigration district of the Three-Gorges region was carried out, accompanying the ongoing construction of dam. Based on the first-hand specimens collected for last many years and historical records, we found that there were about 1784 higher plant species, belonging to 762 genera, 170 families, which accounted for 59.19%,75.30% and 85.85% of total amount of species, genera and families of the Three-Gorges region, including 27 species specific to these two districts. The shrub and grass communities were mostly distributed along the low altitude riparian zone of Yangzi River, largely influenced by dynamic water level of the Three-Gorges reservoir. The measurement of Shannon-Wiener and Pielou evenness indices on 21 Masson Pine communities distributed in the Three-Gorges reservoir area was carried out, and results showed that the biodiversity of shrub layer was the most higher, the grass layer middle, and the tree layer the lowest. Among the 11 typical shrub communities in this region, the abundance of shrub layers of Form.Rhus chinensis, Form.Cotinus coggygria var.cinerea, Form.Vitex negundo var.cannabifoliaand and Form.Coriaria sinica were relatively higher, which were 16,26,29 and 15,respectively. These four shrubs also showed high biodiversity index (H′), which were 1.791,3.427,2.949 and 1.718, respectively. While among the 9 grasslands mainly distributed along riparian zone, 4 grassland communities with higher altitude (Form.Dicranopteris dichotoma, Form.Miscanthus floridutus, Form.Imperata cylindrica var. major and Form.Arthraxon hispidus) showed higher abundance and biodiversity, which were 1.697, 1.354, 1.144 and 1.018, respectively. Considering the submersion district and the immigration district, there were 22 vegetation types threatened by submersion, including 4 woody plant communities, 9 shrub communities and 9 grassland communities. The 6 shrub communities of Form.Securinega wuxiensis, Form.Bauhinia brachycarpa, Form.Geum aleppicum, Form.Distylium chinense, Form.Buxus henryi and Form.Myrsine africana would be fully submerged. and part of Adianthum reniforme var.sinensis and Buxus ichangensis would be submerged. At present, plant species conservation and monitoring stations in the Three-Gorges region have been constructed, and more than 200 plant species have already been transplanted and conserved, including 37 threatened species listed in the China Plant Red Data Book and 11 dominant species of local communities.