An interface control circuit including a physical layer receiver, a lane receiver, a bridge circuit, a transmitter command encoder, a lane transmitter and a physical layer transmitter is provided. The physical layer receiver receives and converts serial data into parallel data, and determines to transmit the parallel data in a high speed transmission mode or a low power transmission mode according to the serial data. The lane receiver receives and decodes the parallel data. The bridge circuit outputs the decoded parallel data. If the serial data includes a read command, the transmitter command encoder encodes the parallel data. The lane transmitter receives target parallel data from the bridge circuit, and transmits the target parallel data in the low power transmission mode according to the encoded parallel data. The physical layer transmitter converts the target parallel data into target serial data and outputs the target serial data.