Abstract: Occupational epidemiology aims to explore the effect of occupational hazards on the health of workers and understand ， their mechanisms. It plays an important role in occupational health and occupational medicine.Currently occupational ， ， exposures in the workplace are complex and diverse and multiple factors affect workers´ health at the same time. Therefore it is important to elucidate the pathogenesis of occupational disease caused by occupational hazards and implement early - - intervention. System epidemiology collects data on multi level exposure and multi omics information to conduct network analysis - on the relationship amongrisk factors. and to study the mechanisms of exposures and health outcomes based on multi level data. ， ， ， ， Using the study design of system epidemiology occupational environmental lifestyle and social factors are combined as a ， system to evaluate the health of workers which can better evaluate the adverse health effects caused by occupational hazards. - ， ， The studies base on multi omics design will explore the pathogenesis of occupational diseases at the molecular cellular and tissue levels to evaluate the impact of occupational hazards on workers´ health and to explore interventions from multiple - perspectives to reduce the occurrence of occupational or work related diseases.