Herbaceous communities in coastal wetland along Bohai coast in Shandong were selected to study the species composition and community diversities. The results showed, in study area, there were 83 herb species which belonged to 23 families, 62 genera. Among them, the species of gramineae and compositae were the most, accounting for 34.94% of all plant species. The distributions of plant genera and families in study area were mainly world distribution and pantropical distribution. The Phragmites australis was the most common in herb with the frequency of occurrence as high as 66%. The plants in 50 plots were divided into 12 types of plant communities by Wards least variance method. These plant communities included Phragmites australis community, Phragmites australis + Suaeda glauca community, Phragmites australis + Suaeda salsa community, Suaeda glauca community, Suaeda salsa community, Atriplex centralasiatica + Echinochloa caudate community, Phragmites australis + Miscanthus sacchariflorus community, Salicornia europaea community, Spartina alterniflora community, Imperata cylindrica community, Phragmites australis + Aeluropus sinensis community, and Phragmites australis + Tamarix chinensis + Calamagrostis pseudophragmites community. The species richness index, Shannon-Wiener diversity index, Simpson diversity index varied from 3 to 40, 0.14 to 2.20, 0.05 to 0.84, respectively. The diversity indexes of different plant community types were significantly different. The species evenness index varied greatly, ranging from 0.12 to 0.83 and the dominant species were not obvious. At present, the plant diversity was mainly influenced by natural factors such as climate warming and river blanking and human disturbance such as unreasonable development and utilization of wetland. The study pointed out the laws of wetland protection should be established and improved, the recovery and reconstruction of wetland as well as the propaganda and education should be enhanced, and the wetland should be exploited and utilized reasonably. On this basis, the coastal wetland ecosystem can be developed sustainably.