Abstract: In the context of the Internet of things, traditional blockchain faces challenges such as insufficient scalability, high costs, and low block generation efficiency. The introduction of the structure of directed acyclic graph(DAG) can effectively enhance the concurrency of the blockchain system, but it also brings about problems such as heavy network load and difficult to achieve consistency. To address these issues, a DAG blockchain model combined with a network sharding scheme is designed. Based on this, an improved Byzantine fault tolerance consensus algorithm is proposed. The nodes in the network are divided into several groups through community mechanism discovery by the proposed algorithm. In each group, candidate nodes are selected through a trust scoring mechanism. Subsequently, a verifiable random function is employed to select primary nodes, followed by an enhancement of the consensus process based on an aggregated signature scheme. Simulation results demonstrate that the proposed algorithm can reduce transaction latency and effectively increase system throughput.

Key words: blockchain, directed acyclic graph, network sharding, Byzantine fault tolerance consensus