Ethereum reduces the risk of a 51% attack through the PoS mechanism, introduces staking withdrawals, and implements penalty mechanisms to enhance node security; Layer 2 solutions (such as Rollup) reduce the mainnet load and lower the probability of single points of failure; the security team continuously optimizes smart contract vulnerability detection tools and collaborates with auditing agencies to improve code security standards. Research on post-quantum cryptographic algorithms is advancing simultaneously to prevent future computational threats. However, the complexity of technology may lead to new vulnerabilities, necessitating a balance between decentralization and security, while community governance and developer collaboration remain core defense barriers.