The present invention is related to an interface design for multimedia data transmitting, which can provide a working interface in a data storing device or a communication device, using the working interface can provide the connecting facility between a multimedia device and computer system and improve the traditional high speed differential signals to portable digital data processing device. The present invention also provides a multimedia storage device, being inserted into a connector of a computer device or a portable device so that the computer device can transmit data to or receive from the portable device, wherein, the multimedia storage device comprises: printed circuit board, for conveying the following elements, having at least one terminal been formed on one end of the printed circuit board and exposed outwardly, wherein one end of the printed circuit board can be inserted into the connector; controller, positioned on the printed circuit board and coupled to the terminal, a working interface of the controller having a parallel data transmission with synchronous clock mode and a differential signal transmission mode, for controlling adaptive data transmission rate and power consumption; and storage unit, for storing data.