Microlens array optical film is a printing substrate for achieving naked-eye 3D display effect. The work aims to study the methods of fabricating optical films for microlens arrays and the factors affecting them during fabrication. Roll-to-roll UV-LED light-cured micro-nano imprinting process was used to scale up the manufacturing of optical films with positive hexagonal apertures and honeycomb rows of microlens arrays through customized micro-nano imprinting molds. The PET film used had good surface smoothness and high transmittance, whose mean square error of surface roughness was about 0.083 μm, and the transmittance in the visible light band was about 90%-93%. So the PET film used was conducive to the formation and manufacturing of microlens arrays and the presentation of excellent optical properties of the optical film. The UV-LED imprinting photoresist used had low viscosity (250 Pa.s, 25 oC), good interface performance (contact angle 93o), and small curing volume shrinkage (3.5%), which was conducive to the filling of mold groove by the photoresist and the formation and demolding of microlens array. For the micro-nano imprinting manufacturing process, appropriate imprinting force should be selected to ensure that the photoresist could fully fill the mold grooves, but also to avoid damage to the mold due to extrusion and deformation of the structure of the microlens array. When the imprinting speed was controlled at 5-7 m/min, the replica precision of the microlens array was higher and the molding quality was more stable, and bubble defects and pull-off defects would not occur. The roll-to-roll UV-LED light-cured micro-nano imprinting process is a well-established method for fabricating optical films for microlens arrays.