Data sharing in the IoT environment suffers from inefficiency and privacy leakage, and the CP-ABE (ciphertext policy attribute-based encryption) data sharing scheme becomes a bottleneck of system operation efficiency because it adopts a single authority, which needs to undertake heavy computational work. To solve the above problems, an efficient multi-authority CP-ABE IoT data sharing scheme with completely hidden policies is proposed in this paper. The scheme uses multi-authority CP-ABE to realize fine-grained access control of data, and uses the non-tampering property of the consortium blockchain to ensure the security of ciphertext Hash and key set ciphertext, and adopts MurmurHash3 algorithm to realize the complete hiding of policy to avoid accessing policy to leak users’ private information; and the scheme combines with multi-secret sharing algorithm to improve multi-authority CP-ABE, thus enhancing efficiency of data sharing. The theoretical analysis proves that the scheme can guarantee the security of access policy and secret sharing process. The simulation experimental results show that the proposed scheme has better performance in both policy hiding and secret distribution processes.