Some studies have shown that compared with traditional drying technologies, supercritical CO₂ technology has some advantages, such as a shorter drying time, smaller deformation, etc. Compared with unearthed waterlogged bamboo and wood wares, undersea wooden cultural relics contain more insoluble salts. In the case of long-term preservation and exhibition of cultural relics, the chemical reactions of salts with water, air or the cultural relics themselves will accelerate the aging and corrosion of the cultural relics. In this research, some components from Nanhai Ⅰ shipwreck were taken as the research objects. The experimental results show that under the conditions of 40 ℃ and 20 MPa, the effect of supercritical CO₂ fluid drying on the undersea wooden cultural relics was obvious in that the three-dimensional shrinkage of the samples was lower than or close to those of the healthy wood. After drying, the water content met the requirements of cultural relic preservation and the salt content of the samples also decreased significantly.