Abstract: In recent years, with the rapid development of the economy and society, the global demand for freshwater resources has been continuously increasing, leading to an increasing shortage of freshwater resources worldwide. Desalination of seawater is one of the best ways to solve the problem of freshwater shortage recently. In order to achieve rapid evaporation of seawater, a photothermal material based on a delignified balsa wood (CDW) was prepared, which had a height of 20 mm and a carbonization layer with thickness of 3 mm. Characterization experiments such as SEM, FT-IR, Raman, and UV-Vis-NIR absorption spectrum have confirmed that the prepared material has abundant pores and high solar absorbance, which is beneficial for photothermal evaporation. A small photothermal evaporator with 2D+3D water supplying paths, transferring water to the photothermal material using absorbent paper, was used to evaluate the evaporation performance of CDW. The average evaporation rate of the prepared CDW material is 1.5310 kg/(m²·h). The evaporation rate is higher than the directly carbonized balsa wood. The comparison between the above results and that without water supply confirmed that the absorbent paper can steadily supply water to the material. The advantages of the 2D+3D water supplying structure are also observed when compared with the 3D water supplying structure.