Method and system applied to duplicate data between USB devices

The present invention provides a method and system applied to duplicate data between USB devices, which could control the data transfer between a source USB device and at least one target USB device without the assistance of a computer. The duplication system according to the present invention employs a central processing unit, which employs at least one serial interface engine circuit to respectively connect to the source USB device and those target USB devices for controlling these serial interface engine circuits, so as to transfer the digital data in the source USB device to those target USB devices; and a data buffer unit, which is connected to these serial interface engine circuits and the central processing unit for providing the memory buffer space required in the digital data duplication process.