In the research of e-commerce big data, constructing a reasonable research framework is crucial. In this chapter, we comprehensively introduce the technical system of e-commerce big data in a bottom-up manner. In summary, the technical system of e-commerce big data can be divided into three levels: the infrastructure layer, the big data layer, and the model layer. The infrastructure layer addresses the issues of data sources and acquisition, completing data preparation; the big data layer preprocesses the data, while adopting a secure and efficient method for storage, ensuring the efficiency and security of data access; and the model layer analyzes and mines the data, fully discovering the value of the data.