Blockchain is a decentralized infrastructure widely used in emerging digital cryptocurrencies. With the fast development of blockchain technology, there are many new achievements in industry and academia. As a decentralized, shared and encrypted distributed ledger technology, blockchain has three distinctive features: decentralization, traceability, and non-tampering. Therefore, the blockchain technology has been used to implement transaction autonomy, save regulatory costs, and improve security. Its birth was even considered to be the fourth industrial revolution. However, the blockchain is still at an early stage of development, and has not been widely applied in practices. One of the main reason is the low performance issue. In order to better understand the state-of-art of the blockchain, we first introduce the architecture and consensus protocols of the current mainstream blockchain systems, then analyze some open source blockchain benchmarking tools, and summarize some blockchain systems optimization methods. Finally, we propose some suggestions for future development of blockchain systems.