The embodiment of the invention provides a blockchain transaction input selection method based on the genetic algorithm. The method relates to the technical field of blockchains and comprises the steps of inputting a set UTXOs and a target value target; traversing the UTXOs, and calculating the current balance total; judging how to output according to the total size, the amount of money of each UTXO in the UTXOs and the target size; when total is larger than target and UTXO larger than target does not exist in the UTXOs, adopting the UTXOs for representing that UTXO is larger than target; sequentially adding the numbers in the UTXOs from large to small until the sum is greater than or equal to target, stopping adding, recording the number num of addition factors, taking the combination ofthe addition factors as an individual of the initial population, and randomly generating the remaining M-1 individuals (M is the population size); and searching the best transaction input selection result by using a genetic algorithm. The sum of the amounts of the UTXO combinations obtained through the method is closer to the target output amount, the number of transaction inputs is minimum, the optimal transaction input selection result can be obtained, and the liquidity of UTXO with the small amount is greatly improved.