A method for on-site repairing of a surface of a component in a wind turbine is provided. In the method, a digital model of the surface is generated using a scanning device. The digital model represents the surface in damaged state. Thereafter, using a processor, a repair scheme for the surface based on the digital model and on a desired state of the surface is generated. The desired state represents a post-repair state of the surface. Consequently, the repair scheme is provided to a 3D printing arrangement. Finally, in the method, one or more selected materials are printed, using the 3D printing arrangement, on the surface to be repaired, wherein the printing is performed according the repair scheme and results in repair of the damaged surface.