To explore the relationship between prosocial risk-taking behavior and cyberbullying bystander behavior among college students, a survey was conducted among 595 college students using the Prosocial Risk-Taking Behavior Scale, Positive Psychological Capital Questionnaire, Interpersonal Trust Scale, and Cyberbullying Bystander Behavior Questionnaire. The results showed that: (1) Prosocial risk-taking significantly and negatively predicted college students’ bystander behavior in cyberbullying, with positive psychological capital playing a partial mediating role in this relationship; (2) Interpersonal trust played a moderating role in both the direct and indirect paths between prosocial risk-taking behavior and college students’ bystander behavior in cyberbullying. High levels of interpersonal trust enhanced the positive effects of prosocial risk-taking behavior and positive psychological capital on college students’ bystander behavior in cyberbullying, while low levels of interpersonal trust weakened these effects. This study provides empirical evidence for colleges and universities to enhance students’ mental health and sense of social responsibility through designing prosocial behavior intervention programs and fostering a high-trust campus environment.

prosocial risk-taking behavior, cyberbullying bystander behavior, positive psychological capital, interpersonal trust, college students