The blockchain has been hailed by the Wall Street Journal as the biggest financial innovation in humans in the past 500 years, while the DeFi distributed financial ecosystem is the most valuable and influential application scenario in 2019 and even in the next few years . DeFi is a blockchain smart contract. The intermediary financial instruments group provides a combination of traditional banking, securities and insurance functions such as borrowing, lending, mortgage, hedging, leverage, options, and insurance, and is more free, safer and more efficient.DeFi, as a landing application in the emerging financial sector, is in the early stages of the booming industry, and now there are more than 1,000 decentralized financial services applications based on Ethereum .