At present， each consensus node of the parallel chain needs to send its own consensus transaction to the main chain to participate in the consensus. As a result， a large number of consensus transactions occupy the block capacity of the main chain seriously and waste transaction fees. In order to solve the above problems， an optimization scheme of parallel chain consensus algorithm based on BLS （Boneh-Lynn-Shacham） aggregate signature technology was proposed by combining bilinear map technology with the characteristics of the same consensus data and different signatures of consensus trades on parallel chain. Firstly， the transaction data was signed by the consensus node. Then， the consensus transaction was broadcasted by each node of the parallel chain and the message was synchronized internally through P2P （Peer-to-Peer） network. Finally， the consensus transactions were counted by Leader node. When the number of consensus transactions was greater than 2/3， the corresponding BLS signature data was aggregated and the transaction aggregate signature was sent to the main chain for verification. Experimental results show that compared with the original parallel chain consensus algorithm， the proposed scheme can effectively solve the problem of consensus nodes on the parallel chain repeatedly sending consensus transactions to the main chain， save transaction fees with reducing the occupancy of the storage space of the main chain， only occupy 4 KB of the storage space of the main chain and only generate a transaction fee of 0.01 BiT Yuan （BTY）.