This study was carried out to investigate the incorporation effect of green manure crops (GMC) such as the hairy vetch on improvement of soil environment in reclaimed land during sorghum${ imes}$sudangrass hybrid (SSH) cultivation over the past three years from 2009 to 2011. Plots consisted of conventional fertilization (CF) and incorporation of GMC were divided by rates of additional nitrogen fertilizer ($100kg;ha^{-1}$) and decreased percentage of 30 50 70 100 fertilization in addition to non nitrogen fertilization (NNF). Soil physico-chemical properties, growth and yield potential were examined. The results were as follows. The testing soil was showed strong alkaline saline soil with low organic matter contents and less available phosphate while exchangeable sodium and magnesium were higher. Soil salinity was increased during cultivation of summer crop. However, SSH was not affected by salt content. The fresh weight of GMC at incorporation time was $18,345kg;ha^{-1}$. Content of total nitrogen at incorporation time was 3.09% and the C/N ratio was 12.8. Fresh and dry matter yield of SSH were higher in the order of 30%, CF, N50%, N70%d, N100%, and NNF. Fresh and dry matter yield of SSH increased in the order of CF ($55,050kg;ha^{-1}$, $16,250kg;ha^{-1}$), N contents from 30% to 9%. Soil physical properties, such as bulk density were decrease with incoporation of GMC, while porosity was increased. Soil chemical properties, such as pH was decreased while content of exchangeable calcium, available phosphate, and organic matter were increased. Also contents of exchangeable sodium and potassium were decreased with incorporation of GMC than those before experiment. Thus, we assumed that incorporation of hairy vetch was more effective that can lead to reduce chemical nitrogen fertilizer and to improve soil environment in cultivating SSH on Saemangeum reclaimed land.