The present invention provides a method for automatically adjusting volume of an audio device, including steps of: S1, obtaining user identity information; S2, detecting an actual environmental volume; S3, determining user hearing condition according to the obtained user identity information, and adjusting a volume of the audio device according to corresponding relationship of user hearing condition, environmental volume and target volume of the audio device, so that the volume of the audio device reaches a target volume corresponding to the detected actual environmental volume and the determined user hearing condition. Accordingly, the present invention further provides an audio device for automatically adjusting volume. With the present invention, the volume of the audio device can be automatically adjusted according to environmental volume with respect to different users.