Based on the study of stretch forming process of large aluminum alloy skin with a large length to width ratio and the analysis and comparison of traditional stretch forming process, a new process of skin stretch forming of longitudinal stretch forming with die was proposed. The forming defect during the skin stretch forming process was analyzed by combining the numerical simulation with experiments. Simulation results show that equivalent stresses are distributed uniformly and up to the yield limit so as to reduce the springback effectively. The springback can be controlled within 0.5 mm for skin, whose length to width ratio is larger than five. Therefore, aluminum alloy skin with large length to width ratio can be manufactured by longitudinal stretch forming with die, which not only saves materials and reduces requirements on equipment, but also obtains high precision and high-quality skin parts.