In the years 1980-1985, on-the-spot investigations were carried out on afforestation in the whole seaboard area of Jiangsu province. The writer is of the opinion that some site factors, such as climate, microtopography and soil are intimately correlated with the distribution and growth of tree species.The tree species for seaboard afforestation fall into two categories-pioneer species and succession species. Pioneer species are those that can establish themselves along the seashore in the adverse ccologic environment. As the pioneer forest is established, and site quality ameliorated, then succession species arc suitable to form new stands. Although succession species are of low adaptability to the adverse environment, they have high ecologic and economic values. A great variety of tree species can be chosen for different purposes of plantation.The land for seaboard afforestation with pioneer species can be chiefly classified into site-quality-type groups.With 30 years’ practice of sea board afforestation, it is believed that Robinia pseudoacacia and Amorpha fructicosa have been successfully used as pioneer species planted in site-quality-type-groups 1, 5, 10, 11.According to the nature of succession species and our specific afforestation requirements, succession species may be classified into 6 groups.In addition, some other species which can be planted for bank protection are to be included, too.