<p>The secure sharing of medical data is crucial for mining its value. The centralized storage solutions of medical data face issues like single points of failure and privacy breaches. In medical services, it is crucial to analyze multiple sets of health information for the same user, encrypted data should be linked together. If the user has a health risk or the ownership of the data is disputed, the data producer needs to be traced. The current data sharing schemes lack data linkability and traceability. To address these issues, firstly, we propose a novel ring signature scheme with linkability and traceability, which can hide the users’ identity. In our definition, it adds a linking algorithm and a tracing algorithm. The linking algorithm can determine whether multiple sets of data belong to the same data producer. Data ownership and the user’s real identity can be traced by the tracing algorithm. Secondly, we propose a blockchain-based medical data sharing scheme by using our proposed ring signature, which solves the problem of centralized storage. Lastly, simulation experiments show that our ring signature scheme is efficient, and the medical data sharing system is feasible.</p>