The invention discloses nanometer cellulose functional doped modified paint and a preparation method thereof. According to the nanometer cellulose functional doped modified paint and the preparation method thereof, the nanometer cellulose functional doped modified paint with one-dimensional nanometer dimensions (5-100 nm) is adopted for forming a compound system composed of a soft resin macromolecular chain structure and a hard nanometer cellulose structure with an ultra-high length-diameter ratio, surface functionalization of nanometer cellulose, a principle of the nanometer cellulose of interface structure toughening and the advantage that the one-dimensional nanometer cellulose and a macromolecular chain form a cross net are used, the tenacity, the impact resistance, the hardness and the surface strength of a paint surface layer are greatly improved, and the defects of cracks, chaps and the like, of a pant surface, caused by high or low temperature in a use process of the paint subjected to curing are overcome. The preparation method of the nanometer cellulose functional doped modified paint can be suitable for water-based paint or oil paint, and a paint product which is modified and prepared through a technology has excellent tenacity, hardness and surface strength, is low in cost, and can be applied in the field of multiple materials of woodware, metal, automobiles, plastic, glass, building surfaces and the like on a large scale.