As a method different from traditional data analysis, big data can provide powerful information retrieval, information processing and information judgment tools for criminal investigation, crime prevention and criminal trial, thus positively influencing the maintenance of a good criminal operating environment in many aspects, such as promoting judicial openness, grasping and guiding public opinion, understanding judicial operation, objectively evaluating judicial staff and rationally allocating judicial resources, and providing unprecedented empirical analysis and empirical data for theoretical research. At the same time, however, it is difficult to strike a balance between the fight against crime and the protection of the rights of individual citizens, and to see how machines can be used in predicting crime, and sentencing, and how to objectively confront the empirical patterns of criminal justice derived from big data analysis in theoretical research. The new issues raised by big data in criminal justice, such as the development and innovation of criminal justice theory itself, can likewise not be ignored.