Abstract: An apparatus for automatically selecting alert option of a communication device is provided. The apparatus includes a noise detection unit for collecting a current ambient noise, and generating a quantified value of the current ambient noise according to the current ambient noise collected; and a central processing unit (CPU), including a detecting module for detecting the communication signal from the receiver, enabling the noise detection unit to perform the corresponding function, and determining a volume level of the current ambient noise according to the quantified value of the current ambient noise from the noise detection unit; and a controlling module for selecting a current alert option of the communication device according to the volume level of the current ambient noise, and controlling the ringing unit and the vibrating unit of the communication device to perform corresponding functions according to the alert option selected.