Abstract: Blockchain is a new decentralized infrastructure emerging with digital cryptocurrencies. The application scope of blockchain as the underlying technology has already gone beyond digital cryptocurrencies, extending to various fields such as finance, economy, technology and politics. At the same time, quantum technology with great scientific significance and strategic value is developing rapidly. In the coming quantum era, blockchain will face unprecedented opportunities and challenges brought by quantum technology. It is mainly reflected in the following aspects: firstly, powerful quantum computing poses a great threat to the blockchain cryptosystem; secondly, the application of quantum technology in blockchain can effectively improve the security of the system. This paper mainly analyzes the different ways of quantum computing to attack blockchain in the coming quantum era. We also point out the development status and trend of quantum technology enabling blockchain. "Blockchain + Quantum Computing" cross fusion research has great realistic significance and quantum blockchain will become the focus in the future high-tech industries.