Online reading of electronic documents has been very common. Documents could be downloaded or their full content could be read online by those users who have paid for them, while limited content could be previewed by the common users. By this way, documents' owners can realize the control of the use of electronic documents to a certain extent. But there are imperfections in the way. If one user has pay for the documents and downloaded them, he or she could send them to others without any restriction. Therefore, in order to achieve better copyright protection, it is worthy of study and exploring access control method on how to still make some restrictions on documents when they are downloaded. This paper focuses on the method for making some access restrictions on the electronic documents both online and offline. For online documents, access restrictions would be done on registered users, while DES encryption and decryption is used for controlling the downloaded documents. Experimentations show that the proposed method based on DES encryption and decryption technology could control the access to electronic documents more efficiently and give a stronger force on copyright protection.