Reclaimed land and coastal soils have characteristics of poor drainage and high salinity because they are adjacent to the ocean. As salty soil hinders growth of crops, it is necessary to improve drainage performance and desalinize the soil for efficient use of reclaimed land. Bottom ash and oyster shells are produced in significant amounts as by-products and wastes in Korea each year and, if left unattended, can cause environmental problems. Because these materials are large in size, particle size distribution and permeability of the soil can be improved by mixing of such ash and shells. Carbonate, a main component of oyster shell, is known to promote granulation of soil particles and can affect the grain size distribution of the soil. In addition, bottom ash has a porous structure that can improve permeability when it is mixed with soil. Therefore, several experiments and numerical analyses were performed in this study on use of bottom ash and oyster shells as soil improvement materials and drainage materials to improve the desalinization efficiency of reclaimed land. Permeability was improved by about 2.7 times at a 20% mixing ratio and by about 5.5 times at a 40% mixing ratio of oyster shell, and bottom ash was most suitable and effective when used as a material for the drainage layer. Desalinization efficiency was highest when mixing oyster shells at a 40% ratio and using bottom ash for drainage, which increased the efficiency by approximately 2.6 times over 10 days. In conclusion, reuse of bottom ash and oyster shell could improve the efficiency of reclaimed land use.