Against the backdrop of the rapid evolution of cloud computing technology, data storage and processing are continuously migrating to the cloud. Data security and privacy protection have become core challenges that need to be overcome urgently. As an important tool for safeguarding data security in cloud computing, encryption technology plays a crucial role in practice. Traditional encryption methods such as symmetric encryption, asymmetric encryption, and hybrid encryption, as well as emerging technologies like homomorphic encryption, attribute - based encryption, and searchable encryption, and cutting - edge solutions including zero - knowledge proof and secure multi - party computation, are all widely applied in cloud computing scenarios to encrypt and protect data throughout its entire life cycle. This article focuses on reviewing the above - mentioned encryption technologies, aiming to provide a theoretical reference for technological innovation in the field of cloud computing data security and help build a more efficient, secure, and flexible data encryption protection system.