Currently, data silos are a common result of hospitals’ lack of data sharing and interchange. The open access, sharing, and circulation of regional healthcare data, on the other hand, may result in deliberate tampering, theft, misuse, and loss of ownership, all of which could result in patient privacy leaks. Regional healthcare data comprises a significant quantity of sensitive patient information. Because healthcare data is so large and unstructured, it is more difficult to detect and stop targeted malicious attacks like ransomware, data theft, and tampering. A multi-authority attribute hiding blockchain-based electronic medical record (EMR) sharing scheme is presented to address these problems by providing patient privacy and enabling fine-grained access to shared EMRs. We describe the multi-authority attribute-based encryption (MA-ABE) technique, which effectively prevents collusion attacks between users with varied permissions by using various authorities to manage distributed attributes and identifying distinct users through hash functions. To preserve attribute privacy, attributes are divided into names and values and partially hidden using the linear secret sharing scheme (LSSS). An algorithm is meant to update access policies by combining the openness, transparency, and immutability of blockchain technology. To create a traceable policy update chain, this algorithm uploads new access policies to the blockchain and appends policy blocks depending on the access policy update algorithm. The approach achieves traceability of user behavior, data privacy protection, and distributed and reliable access control management under hidden policy circumstances. The suggested technique may successfully ensure attribute privacy while lowering computational overhead thanks to security proofs and experimental research.