A device and a method for updating the function of a monitor according to the invention. By using the USB signal lines directly for data transmission and recording the data of a monitor controller to the erasable programmable read only memory, data update can be achieved. Moreover, the erasable programmable read only memory can be updated by separating the recording path and the normal visual path using a recording path separator of the monitor controller. Compared to the prior art, the device and the method of the invention are more convenient and time saving for function update of the monitor.