A mobile device and information transmission method are provided. The information transmission method is applied to the mobile device in M2M communication and includes the steps of determining whether a base station and the mobile device support transmission of capability information of the mobile device by a General Extension Message and determining whether the mobile device has transmitted the capability information to the base station when the base station and the mobile device support transmission of the capability information by the General Extension Message, wherein when the mobile device has transmitted the capability information to the base station, the capability information is not transmitted by the General Extension Message again.