Focusing on coarse granularity of access control， low sharing flexibility and security risks such as data leakage of centralized medical data sharing platform， a blockchain-based hierarchical access control and sharing system of medical data was proposed. Firstly， medical data was classified according to sensitivity， and a Ciphertext-Policy Attribute-Based Hierarchical Encryption （CP-ABHE） algorithm was proposed to achieve access control of medical data with different sensitivity. In the algorithm， access control trees were merged and symmetric encryption methods were combinined to improve the performance of Ciphertext-Policy Attribute-Based Encryption （CP-ABE） algorithm， and the multi-authority center was used to solve the key escrow problem. Then， the medical data sharing mode based on permissioned blockchain was used to solve the centralized trust problem of centralized sharing platform. Security analysis shows that the proposed system ensures the security of data during the data sharing process， and can resist user collusion attacks and authority collusion attacks. Experimental results also show that the proposed CP-ABHE algorithm has lower computational cost than CP-ABE algorithm， the maximum average delay of the proposed system is 7.8 s， and the maximum throughput is 236 transactions per second， which meets the expected performance requirements.