The invention discloses a highly-transparent anti-ultraviolet nano-cellulose composite film and a production method thereof. The matrix of the composite film is polyvinyl alcohol, and a reinforcing phase is modified cellulose nano-fibers. The production method comprises the following steps: preparing cellulose nano-fibers modified with 2-hydroxy-4-methoxybenzophenone and epoxidized soybean oil; and mixing the modified cellulose nano-fibers with a polyvinyl alcohol-water solution according to a certain mass ratio, and drying the obtained mixture in an oven to obtain the uniform and transparentcomposite film. Raw materials in the invention are derived from biomass, so the composite film is biodegradable, and has good biocompatibility. The shortcoming of poor stability of a small-molecule ultraviolet absorbent is overcome, and the epoxidized soybean oil can be used as a plasticizer to increase the flexibility of the composite film. Nano-particles in the composite film are uniformly dispersed in the matrix, the composite film has a high transparency and can provide a significant anti-ultraviolet effect, and the ultraviolet protection effect can be controlled by controlling the addition amount of the nano-particles in the film.