The Ethereum Security Plan focuses on consensus mechanism upgrades, Layer 2 scalability, and strengthening anti-attack capabilities. The PoS mechanism reduces the risk of 51% attacks, introducing staking withdrawals and penalty mechanisms to enhance node security; Layer 2 solutions (such as Rollup) reduce 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 concurrently to guard against 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 defensive barriers.