Abstract: The 7003 aluminum alloy was extruded for four passes by dual equal channel lateral extrusion (DECLE) with two routes of non-rotation of samples between each pass (route A) and 90° clockwise rotation of samples between each pass (route B). The microstructure and mechanical properties of the alloy after extrusion were studied. The results show that after four-pass DECLE treatment, the grains of 7003 aluminum alloy were refined to nano scale. The parallel curved shear bands were formed in the alloy under route A. The cross shaped shear bands were formed under route B and refined the grains better due to the dislocation segmentation effect. With the increase of DECLE passes, the yield strength, tensile strength and hardness of the samples increased under the two routes. The strength and the hardness under route B were higher than those under route A, but the elongation after fracture was lower than that under route A.