In the face of a large number of consensus nodes in the food alliance blockchain network,due to the low efficiency of the traditional practical Byzantine fault tolerance (PBFT) consensus algorithm,communication energy consumption is too high,which greatly increases the risk of information leakage and data fraud.To solve the above problems,this paper proposes a PBFT optimization consensus algorithm based on agglomerative hierarchical clustering (AHC).Firstly,the AHC algorithm is used to classify and cluster all the consensus nodes. Secondly,PBFT consensus occurs in all clusters in parallel.Finally, the message agreement is reached through the consensus of the master nodes in the cluster.The experimental results show that the improved algorithm can effectively reduce the energy cost and improve consensus efficiency and throughput.