An optical module with an optical film and a positioning frame is disclosed. The positioning frame firmly fixes the optical film of the optical module so as to prevent the deviation of the optical film. The optical film has at least a first lug with a base portion and an expansion portion extending outwardly, wherein the width of the expansion portion is wider than the base portion. The positioning frame has a side wall and a flange. The flange is disposed on the side wall and has a first opening. The flange located at one side of the first opening has a first protrusion extending outwardly the side wall on the two sides of the first opening. The first opening is used to contain the base portion of the first lug, and the expansion portion of the first lug can be disposed under the first protrusion.