To query MEV activities on Ethereum, we first need to know that after a transaction is initiated in Ethereum, the transaction will be placed in the memory pool and wait to be packaged by the miners, then the miners can see all the transactions in the mempool, and the miners’ The power is great, and miners control the inclusion, exclusion, and order of transactions. If someone pays more Gas fees to bribe the miners to adjust the order of transactions in the transaction pool and make a profit. There is a MEV method called “sandwich attack” or “trap attack”. This method of extracting MEV is by monitoring large DEX transactions on the chain. For example, someone wants to buy altcoins worth $1 million on Uniswap, and this A transaction will increase the price of this altcoin a lot. When this transaction is put into the mempool, the monitoring robot can detect this transaction. At this time, the robot will bribe the miner who packaged this block to send a The operation of buying this altcoin jumps in front of this person, and then performs a sell operation after this person’s purchase operation, just like a sandwich, sandwiching this person who conducts large DEX transactions in the middle, thus launching a “sandwich” The person who “attacked” obtained altcoins from it because the person made a large-scale transaction to pull the profit, while the person who made the large-value transaction caused losses.