A laser interference lithography apparatus capable of stitching small exposed areas into a large exposed area includes a body, a laser beam supplying unit, a reflecting mechanism, an L-shaped fixing mechanism and a substrate stage. The laser beam supplying unit fixed onto the body provides a laser beam. The reflecting mechanism is movably and rotatably mounted on the body. The L-shaped fixing mechanism mounted on the body includes a first mounting seat and a second mounting seat. An upright first reflecting mirror is fixed to the first mounting seat. The second mounting seat connected to the first mounting seat fixes a horizontal mask, and is substantially perpendicular to the first mounting seat. The substrate stage, movably mounted on the body and disposed below the second mounting seat, supports a substrate. Thus, a large-area pattern formed by stitching small-area patterns may be obtained. |