The general framework and security demands of digital enterprises are analyzed. The information security system is constructed, which includes physical security, network security, support layer system security, application layer system security, data and documents security. Aiming at the security of internal information security such as data and documents, a comprehensive solution including identity authentication, centralized equipments control, document security management, document encryption, and security audit are put forward. Based on the above information security system, an implementation scheme for typical digital enterprise is proposed.