A copyright protection method is applied to an electronic device. The method includes: obtaining digital data of an audio file via Video on Demand (VOD); determining whether or not the audio file is free to use; determining whether or not the accessing of the audio file is legal if the audio file is not free. Upon a condition that the audio file is free, or the accessing of the audio file is legal and not free, decoding the audio file into analog signals. Upon a condition that digital copyright information is not included in the audio file, inserting into the analog signals the digital copyright information; outputting the analog signals of the audio file along with digital copyright information of the audio file. Upon a condition that the audio file is not free and not legally permitted, indicating the accessing of the audio file is illegal. The electronic device is also provided.