The invention discloses a preparation method and application of ZnO / TiO2 composite powder. The preparation method comprises the following steps: dissolving soluble a zinc salt, a surfactant and butyl titanate in alcohol, and mixing to obtain a raw material liquid; adding a strong base aqueous solution to the raw material liquid under the stirring condition to obtain a mixed liquid; and reacting the mixed liquid at 120-180 DEG C for 8-16h, washing and drying to obtain the ZnO / TiO2 composite powder. The preparation method is relatively low in temperature conditions, good in controllability, simple in preparation and strong in operability, is favorable to industrialized popularization and production, and has wide application prospects. The obtained ZnO / TiO2 composite powder is complete in crystallization, small in original granularity, uniform in distribution and low in agglomeration, and is particularly suitable to be used as an additive for an automobile paint to be applied to the automobile paint, so that the automobile finish coat has the advantages of being plump in lacquer film, level and bright, strong in adhesion force, high in hardness, good in light retention rate, excellent in natural solarization performance and the like.