With the rapid development of information technology, data security issues are becoming more and more prominent, and symmetric encryption, as a common encryption method, has received widespread attention. And among the symmetric encryption algorithms, AES is favored for its high security, efficiency and reliability. This paper firstly introduces the basic principles and technical details of AES algorithm and discusses its specific operation in the process of data encryption and decryption. AES algorithm adopts the substitution-replacement network structure and encrypts the data through multiple rounds of iterative operations, and it has three kinds of key lengths of 128-bit, 192-bit, and 256-bit, which can be selected according to the security requirements, and it has a higher level of security. Then this paper discusses the AES algorithm mainly has four cryptanalysis methods, namely, brute-force cracking, timing attack, linear analysis and differential analysis, as well as the encryption and decryption experiments of the AES algorithm, and the encryption and decryption experiments of the text information using OpenSSL, to evaluate the performance of the encryption and decryption process, and to provide the relevant performance indexes and analysis results. Finally, this paper discusses the application of AES algorithm in various fields. In the financial field, AES is used to encrypt financial transaction data and customer authentication information. In the field of Internet of Things (IoT), AES protects the communication security between IoT devices. In military applications, AES protects the security of military communications and data. These application cases fully demonstrate the importance and wide application of AES in various fields. In summary, this thesis systematically introduces the research and application of AES algorithm in symmetric encryption based on AES algorithm, deeply analyzes the principle, technical details, and applications in various fields of AES algorithm, and puts forward the suggestions for the future research and application. AES algorithm plays an important role in information security protection, and it is of great significance to protect the security and privacy of data.