A method for adjusting ring volume through short message service includes steps of a communication device determining whether a volume adjusting condition is satisfied when there is a missed call; the communication device transmitting a first short message if the volume adjusting condition has been satisfied, wherein a first information element identifier (IEI) is set in the first short message and defined as a volume adjusting request in transfer protocol user data (TPUD) in advance; the communication device determining whether a second IEI is set in a second short message when receiving the second short message, wherein the second IEI is defined as a volume adjusting response in TPUD in advance; and the communication device selectively adjusting a ring volume thereof to maximum level if the second IEI is set in the second short message.