School bullying has become a serious global issue, with bystanders playing a crucial role in these situations. While many bystanders choose to remain passive when witnessing bullying, some decide to take proactive protective actions. This paper reviews the motivations and influencing factors behind bystander protective behavior and proposes effective intervention recommendations based on existing research. Studies show that bystander protective behavior is influenced by multiple factors, including empathy, social responsibility, and group norms. At the same time, the victim’s reactions, the severity of the bullying incident, and the individual characteristics of bystanders also play important roles. This paper further explores how to promote bystander protective behavior by cultivating empathy, reinforcing social responsibility, and creating a supportive environment. Finally, the paper outlines future research directions.