This paper mainly studies the symmetric encryption and decryption technology for multi-user shared data in cloud storage environment. With the popularity of cloud storage technology, more and more users store multi-user shared data on third-party cloud platforms. In order to protect the privacy and integrity of multi-user shared data, encryption technology has become an important means to deal with cloud security challenges [1]. The traditional multi-user shared data encryption technology has some problems in the scenario of multi-user shared data. For example, it is difficult to restrict the access to multi-user shared data after decryption. Therefore, this paper proposes a symmetric encryption technology for multi-user shared data based on access control, which uses attribute encryption to achieve controllable access to multi-user shared data, and uses group cryptography and obfuscation technology to ensure the confidentiality and integrity of multi-user shared data. The experimental results show that this technology not only ensures the security of multi-user data sharing, but also has high efficiency and user friendliness. As a result, it can meet the encryption requirements in large-scale multi-user data sharing scenarios. The research of this technology has certain reference significance for the security improvement of cloud storage field.