An electronic device includes an input unit to generate input signals according to a users input. A storage unit to store audio files, an alarm speaker unit to sound the alarm audio files and execute the alarm commands. In addition, a processing unit to sound the alarm after a system time reaches a preset time period. Moreover, analyses operation type according to the input signals to control the speaker unit to resound the alarm or not sound the alarm after a time period according to the operation type. An alarm method is also provided.