In recent years, the clean water crisis has become a significant environmental challenge. Thus, water desalination has intensified over the past decades. As an energy-efficient, environmentally friendly, economical, and easy-operate technique, capacitive deionization (CDI) has attracted enthusiasm, in which carbon materials play an important role in salt ion removal. Benefiting from the abundance and easy preparation properties, biomass converted carbon has obtained attention in water desalination by CDI. Because of natural porous structure, wood is chosen as the biomass carbon precursor and to study the water desalination performance: Binder-free wood converted carbon sheets were successfully converted from several species of natural wood, and further chemical activation was processed to enlarge the porous structure. We found the pine and balsa converted carbon have a comparable salt adsorption capacity with commercial activated carbon, and activated balsa exhibits an extraordinary improved adsorption performance. The promising results indicate that activated balsa is an excellent material for water desalination.