The invention relates to a USB data transmission device in a high-speed data communication link and a method thereof. The device comprises a USB control functional module connected with a host machine and a central control module, wherein the central control module comprises a DMA controlling unit and an ARM controlling unit connected with the DMA controlling unit, and the DMA controlling unit and the ARM controlling unit are respectively connected with the USB control functional module. The method comprises the following steps: data receiving processing operation and data transmitting processing operation. The USB data transmission device in the high-speed data communication link and the data transmission method thereof completes the data transmission by skillfully adopting the way that a hardware signal directly triggers the DMA, reduce the interruption to the CPU to the utmost extent, obviously lower the load of the CPU, and improve the efficiency and the reliability of the system. meanwhile, the principle is simple and practical, the operating process of the system is stable and reliable, the application range is broader, and especially in the high-speed data communication, the data transmission speed can reach 100 Mbps, which can meet the requirements of application of majority of communication data links.