An adjustable photo-mask for providing variable properties includes a casing and a plate. The casing has a receiving room inside and a plurality of openings, with the openings extending from the receiving room to a front face of the casing. The plate has a plurality of through holes, with an axial direction of the through holes defined as a ray-transmission direction, with the plate slideably received in the receiving room, and with the through holes and the openings totally or partially overlapping in the ray-transmission direction.