The invention disclosed a data transmission system, comprising a first conversion module provided on the host side, used for converting USB data into data in format which may be transmitted by a data transmission module and for converting data in format which may be transmitted by the data transmission module into USB data the data transmission module provided between the host and the monitor, used for data intercommunication between the host and the monitor, and a second conversion module provided on the monitor side, used for converting USB data into data in format which may be transmitted by the data transmission module and for converting data in format which may be transmitted by the data transmission module into USB data. Wherein, the data transmission module is a DisplayPort auxiliary channel (DisplayPort AUX CH). With the invention, the connection of the personal computer host and the monitor may be realized by using only one DisplayPort cable, thereby USB interfaces may be integrated on the monitor. The manner may reduce the complexity and cost of the computer system, and may enhance the user experience.