With the continuous breakthrough of quantum technology, especially the continuous development of quantum technology in the developed countries, the original classical password security measures of Chinese egovernment extranet have been seriously threatened, which must be prevented before the actual threat occurs; Using quantum secret communication to solve the security problem of key distribution in classical cryptography has become an important security measure for cryptographic applications in government affairs, finance and other fields. Based on quantum technology, this paper explores the application of special line encryption, application encryption, data encryption, identifying network attacks based on quantum computing, verifying the robustness of password security and other scenarios in the egovernment extranet, which improves the confidentiality, integrity and availability of the system business data transmission carried on the egovernment extranet to a certain extent.