A light guide element and a lighting fixture are described. The light guide element includes a light guide body, first microstructures and second microstructures. The light guide body includes a first light-emitting surface and a second light-emitting surface opposite to and parallel to each other. The first microstructures are disposed on the first light-emitting surface in rows. The second microstructures are respectively corresponding to the first microstructures and are disposed on the second light-emitting surface. In each of the rows, each of the first microstructures laps over the corresponding second microstructure in part in a normal direction of the first light-emitting surface. Overlapping ratio of the first microstructures and the corresponding second microstructures become greater from one end of one of the rows to the other end of the one of the rows.