The invention relates to a method and a system of copyright protection, which are used for a portable terminal to download data; the invention belongs to the technical field of digital copyright protection and relates to the method and the system of copyright protection in the process of data information transmitting. In the invention, a Bluetooth equipment address is taken as the encrypted information of downloaded data to encrypt the downloaded data, namely, before the data is transmitted or downloaded to the portable terminal which is provided with a built-in Bluetooth module, the Bluetooth equipment address of the portable terminal is added to the appropriate position of the downloaded data and then sent to the portable terminal; when the data is operated or played, the Bluetooth equipment address is extracted from the built-in Bluetooth module of the portable terminal and is used for comparison with the encrypted information added in the encryption of the data; if correct, the data document is operated or played, otherwise, operation is stopped. The method of the invention is characterized by simple encrypting and decrypting, low resource occupancy rate to the equipment, goodconfidentiality, convenient use, and the like, which is specially applicable to the potable terminal with limited hardware performance.