In view of the shortcomings of big data security and privacy protection in cloud environment, a big data security architecture was proposed in this paper. Based on blockchain technology and trusted data cloud center, data security architecture adopts the ideas of trusted authentication, intrusion detection, data segmentation, and decentralized storage and applies Amazon AWS log processing service, PairHand user authentication protocol, and Hadoop data analysis framework to realize dig data security and privacy protection in the cloud environment. This paper realizes system initialization and user authentication, hierarchical data storage, decentralized storage, and user security access. The experimental results show that the system architecture can ensure data security and data access speed, which can provide necessary reference for cloud security.