Outsourced Database Security - With the rapid development of information technology, it becomes more and more popular for the use of electronic information systems in medical institutions. To protect the confidentiality of private EHRs, attribute-based encryption (ABE) schemes that can provide one-to-many encryption are often used as a solution. At the same time, blockchain technology makes it possible to build distributed databases without relying on trusted third-party institutions. This paper proposes a secure and efficient attribute-based encryption with outsourced decryption scheme based on blockchain, which can realize flexible and fine-grained access control and further improve the security of blockchain data sharing.