Cross-chain technology is considered to be the holy grail in the blockchain field and a key technology to realize the interconnectivity of all chains. The importance of this is often compared to TCP/IP on the Internet. It was the TCP/IP protocol cluster that provided the point-to-point linkage mechanism, standardizing how data should be encapsulated, addressed, transmitted, routed, and received at its destination, that led to the global network of terminals that evolved into what we call the Internet today. With the rapid development of the blockchain industry, all kinds of public chains and license chains continue to emerge. The vast majority of chains cannot be connected to each other due to technical, ecological, competitive and other reasons, which leads to the disconnection of users, assets, applications and data, forming the "island effect". Therefore, in the multi-chain era, the market demand for cross-chain is becoming more and more clear. Whether it is the new public chain or Ethereum Layer 2, asset Bridges for cross-chain use seem to have become indispensable. Fundamentally speaking, the main reasons for this situation are: the diversification of user needs and the limitation of blockchain scalability. In order to connect islands into continents, the industry is actively exploring cross-chain technology.