Proposed in this paper is a relative coupling-based multi-motor synchronous control algorithm for the high-power all-electric bending machine applied to the multiaxial synchronous bending of sheet metal. In this algorithm,multiple motors drive according to the position deviation synchronously,and the rapidity of each motor is improved by adopting the equivalent velocity and the acceleration feedforward,thus implementing preferable synchronization and meeting the accuracy requirements of sheet metal bending. Moreover,a modeling simulation and a practical test are performed on a bending-machine experiment platform. The results demonstrate that the proposed synchronous control algorithm is of high synchronization accuracy and strong robustness.