Blockchain 3.0 is the third stage of the development of blockchain technology and the core of building a value Internet. Its innovations in sharding, cross-chain and privacy protection have given it a wide range of application scenarios and research value. It is highly valued by relevant people in academia and industry. For the development, technologies and applications of blockchain 3.0, the relevant literature on blockchain 3.0 at home and abroad in the past five years were surveyed and reviewed. Firstly, the basic theory and technical characteristics of blockchain were introduced, laying the foundation for an in-depth understanding of the research progress of blockchain. Subsequently, based on the evolution trend of blockchain technology over time, the development process and various key development time nodes of blockchain 3.0, as well as the reasons of the division of different stages of development of blockchain using sharding and side-chain technologies as benchmarks, were given. Then, the current research status of key technologies of blockchain 3.0 was analyzed in detail, and typical applications of blockchain 3.0 in six major fields such as internet of things, medical care, and agriculture were summarized. Finally, the key challenges and future development opportunities faced by blockchain 3.0 in its development process were summed up.