The invention discloses a nano titanium dioxide-based wood preservative. A preparation method is characterized by comprising the steps of modifying nano titanium dioxide, preparing acrylic emulsion, preparing acrylic acid aqueous dispersion, and uniformly mixing the acrylic acid aqueous dispersion with tebuconazole, carbendazim and imidacloprid, thus obtaining the nano titanium dioxide-based woodpreservative. The wood preservative provided by the invention has broad-spectrum bactericidal and insecticidal action, is good in preservative effect, and is relatively low in toxicity and harmless tothe environment and a human body.