To address the issues of poor user privacy protection and insecure communication in the Internet of Medical Things(IoMT) environment, we propose a blockchain-based lightweight mutual authentication scheme for the IoMT. Firstly, our scheme is a two-factor authentication scheme that uses certificates and feature information for identity authentication. Secondly, we use elliptic curve cryptography and the Chinese remainder theorem to design a lightweight identity registration and authentication algorithm. This algorithm can aggregate multiple identity information of users for verification, while achieving efficient user identity authentication and ensuring the security of user identity information. Finally, we combined non-fungible tokens (NFT) with user device information, and through a composable NFT solution, we ensured the uniqueness and immutability of user identity information on the blockchain, while facilitating user identity management. The formal security analysis based on AVISPA has proven the security of our scheme. Performance analysis shows that the proposed scheme has low communication and storage overhead. We simulated the proposed scheme on the Ethereum platform using the Solidity language and conducted latency and throughput analysis of our smart contracts using the stress testing tool Hyperledger Caliper. The results illustrate the practicality of our scheme.