Abstract To explore the influence of the occurrence and development of bystander behavior in cyberbullying among adolescents, the paper reviews the factors influencing bystander behavior from the perspective of social ecosystem theory at the individual level, microsystem (family and school factors), peripheral system (contextual factors), macrosystem (cultural factors) and digital environment (media factors). It is pointed out that the future research needs to further explore the internal interaction of micro system, the influence of time system and technological development on bystanders, and the complex interaction between social ecosystems, and design feasible intervention strategies to transform passive bystanders into active interveners.