Decentralized finance began to flourish in the second half of 2020, and information security incidents broke out one after another, mainly related to code security.This research intends to use the current attack process of various common DeFi projects to analyze the vulnerabilities, including flash loans, oracles, governance projects, etc., and provide smart contract security writing or solutions for cases, so that decentralized financial projects can be more intelligent The contract part can fundamentally slow down attacks from outside.