Modification of Pinus yunnanensis using SiO2–TiO2 was carried out via the sol–gel method. The aim was to improve the hydrophobicity, aging resistance, and photocatalysis of the wood surface via the formation of new chemical bonds with penetrated SiO2 and TiO2. The air-dried P. yunnanensis wood underwent penetration, gelation, aging, and drying. The wood was exposed to high temperatures for modification, and its microstructure, composition, photodegradability, resistance to aging, dimensional stability, and hydrophobicity were then determined. The results indicated that during modification, SiO2–TiO2 gel was generated in the wood, and the content of the gel increased as penetration time was extended. No structural change in the wood was observed. Meanwhile, chemical bonds were formed among SiO2, TiO2, and wood. The contact angle of the modified wood increased noticeably relative to that of unmodified wood. This increase indicated a noticeable increase in the hydrophobicity of the wood surface. The modified wood exhibited high photocatalytic degradation; however, its durability was not evident. The water absorption and thickness swelling of the modified wood markedly increased. After ultraviolet-aging resistance testing, the color change in the surface of the modified wood was noticeably less than that of the unmodified wood.