<p>Articulated robots have been widely used in various aeronautic machining tasks. However, a single robot can not provide the required machining quality due to its low stiffness. Although a dual-robot system with a rigid connection can improve overall system stiffness, it often generates relatively large internal forces due to synchronization errors between the two robots. To address this issue, a novel dual-robot milling system with a flexible linking component is developed. The proposed system improves the robot stiffness without requiring strict synchronization between the two robots. A stiffness model is established for proposed the dual-robot system. The results calculated through this model show that the system stiffness is higher than that of a single robot. This further indicates the flexible linking component is an optimal design which balances stiffness requirements with force transmission constraints. Then, a planar double-spiral disk-shaped flexible linking component is designed by considering the milling forces, the load capacity and stiffness of the robots. Finally, several experiments are conducted to validate the proposed dual-robot system. The end deformation of the dual-robot is smaller under static loading, which verifies that the stiffness of the proposed system is higher than that of a single-robot stiffness. Compared with a rigid connection, the connection of the flexible linking component effectively reduces the internal forces caused by synchronization errors. Furthermore, actual milling tests show that the machining errors are significantly reduced, both machining quality and efficiency are improved by the dual-robot system.</p>