The invention relates to a photocatalytic coating with a micro-nano structure and a preparation method for the photocatalytic coating, and belongs to the technical field of catalysts. The preparation method comprises the following steps: coating nano titanium dioxide with hydroxyapatite to form composite material suspension liquid; and spraying and depositing the composite material suspension liquid to the surface of a base material through a thermal spraying process, thereby obtaining the nano titanium dioxide photocatalytic coating coated with the nano hydroxyapatite material. The HA-TiO2 nano composite photocatalytic coating prepared by the preparation method has the characteristics of a porous micro-nano structure, a high specific surface area, excellent adsorption performance and a strong photocatalytic property; and the preparation method is simple to operate, is low in cost and is suitable for industrial production.