As an important institutional expression of people's justice and judicial democracy, the people's assessors system is the judicial path to realize people's democratic rights in the new era. Starting from the theoretical perspective of “whole-process people's democracy”, this paper takes the people's assessors system as the research target, and empirically tracks the degree, organization, scope and performance of citizens' participation in justice based on judicial big data. It has found that the people's assessors system can provide a wide space for the implementation of the “whole-process people's democracy”. The “whole-process people's democracy” contained in the people's assessors system can profoundly influence judicial decision-making. The vitality of “whole-process people's democracy” generated by the people's assessors system needs to be further released. For people's justice, “whole-process people's democracy” not only fits the essential requirement of “letting the people feel fairness and justice in every judicial case”, but also indicates the birth of a new judicial governance technology.