Abstract: The consensus mechanism is the core of blockchain technology, and the consensus algorithm is the specific technical means to achieve this mechanism, which ensures the consistency and correctness of the blockchain database, and is crucial to the system performance of the blockchain such as security, scalability and throughput. Thus, first, from the perspective of the underlying storage of blockchain technology, consensus algorithms were divided into two categories: chain and graph, and classifies and reviews the working principles, optimization strategies and typical representative algorithms of different types of consensus algorithms. Then, in view of the complex application background of blockchain, the mainstream improved algorithms of chain structure and graph structure consensus algorithm were comprehensively sorted out, and the main line of consensus algorithm development was given, especially in terms of security, and the advantages and disadvantages and possible security risks were pointed out. Finally, from multiple dimensions such as security, scalability, fairness and incentive strategy, the challenges faced by the current blockchain consensus algorithm were discussed in depth, and its and development trend are prospected, so as to provide theoretical reference for researchers.

Key words: blockchain, consensus algorithm, distributed system, Byzantine fault tolerance, chain storage structure, graph storage structure 
 

摘要： 共识机制是区块链技术的核心，共识算法则是实现这一机制的具体技术手段，它确保区块链数据库的一致性和正确性，对区块链的安全性、可扩展性和吞吐量等系统性能至关重要。因此，首先，从区块链技术的底层存储的角度，将共识算法分为链式和图式两类，对不同类型的共识算法的工作原理、优化策略以及典型代表性算法进行分类综述。其次，针对区块链的复杂应用背景，分别全面梳理链式结构和图式结构共识算法的主流改进算法，给出共识算法的发展主线，特别是在安全性方面进行深入的比较，指出它们存在的优缺点和可能面临的安全风险。最后，从安全性、可扩展性、公平性和激励策略等多个维度，深入讨论当前区块链共识算法面临的挑战，并展望其发展趋势，为研究者提供理论参考。

关键词: 区块链, 共识算法, 分布式系统, 拜占庭容错, 链式存储结构, 图式存储结构