A mobile communication device is provided in the present disclosure. The mobile communication device includes a prompting module, a detecting module, a determining module and a control module. The prompting module includes a speaker and a vibrator. The detecting module is configured for detecting a vibrating noise corresponding vibration of the vibrator. The determining module is configured for determining whether the vibrating noise is less than a threshold value. The control module is configured for controlling an operation state of the speaker according to a determining result of the determining module. The present disclosure further provides a prompting method of the mobile communication device.