Research on Trusted Execution Environment (TEE)-based smart contracts in blockchain privacy and security focuses on leveraging hardware-assisted secure enclaves to execute smart contracts confidentially and reliably. TEEs provide isolated environments where contract code and sensitive data can be processed without exposure to the blockchain nodes or external attackers, mitigating risks such as data leakage, tampering, or malicious manipulation. Studies explore integrating TEE with blockchain to enable privacy-preserving computations, verifiable execution, and secure off-chain data handling, particularly in applications like finance, healthcare, and decentralized marketplaces. Research also addresses challenges including enclave performance, scalability, and potential side-channel attacks, as well as hybrid approaches combining TEEs with cryptographic techniques such as zero-knowledge proofs. Overall, TEE-based smart contracts enhance blockchain security and privacy by providing trusted, confidential, and verifiable execution environments.