Wood is an ideal green building material because of its high strength-to-weight ratio, renewable nature, and excellent heat insulation/nosie reduction/humidity control performances. However, rich nutrients make wood materials easy to microbial erosion, which limits application in the construction field. Herein, a novel anti-mildew technology is reported, which fills Ti0.87O2 nanosheet into the open pores of wood materials spontaneously. Based on the high light transmittance of the titanium oxide (Ti0.87O2) nanosheet, the as-prepared composite wood retains the original texture and color of wood. There are multiple coordination bonds between the hydroxyl of cellulose/lignin and Ti4+ of titanium oxide, which enhances the stability of the interface between the wood material and Ti0.87O2 nanosheet. The filling medium (Ti0.87O2) cuts off the transmission path of oxygen, water, nutrients and microorganisms, which makes the composite wood have good mildew resistance. Therefore, the modification technology makes wood have great application potential in the field of structure and decoration.