This chapter, “Main technologies of e-commerce and financial payment,” delves into the key technologies underpinning modern e-commerce and financial payment systems. The chapter begins with an overview of the Internet, explaining its basic working principles, the development of the Internet in China, and the future prospects with Web 4.0. It then explores big data, detailing its characteristics, technical classifications, and typical applications. Cloud computing is also discussed, highlighting its features and application areas. Additionally, the chapter examines blockchain technology, describing its characteristics and various application scenarios. Finally, it covers artificial intelligence, focusing on its core technologies and applications in the financial sector and e-commerce.