The rapid development of computer technology and the extensive coverage of computer network have promoted the rise of Chinese computer industry in the 21st century. But while computer technology benefits mankind, it also carries great potential risks. For example, the loss or damage of key data, the disclosure or abuse of personal privacy, has undoubtedly brought serious losses to human society. Therefore, it is necessary to develop and make good use of data encryption technology, and to increase the defense line for computer network security, so as to maintain computer network security and reduce the possibility of information being tampered with or stolen. Based on the current situation of computer network security and the necessity of strengthening computer network security, this paper analyzes the factors affecting computer network security, points out the classification and value of data encryption technology, thus provides a scientific theoretical basis for the application of data encryption technology in computer network security.