Displaced aggressive behaviour is associated with many negative outcomes. Although certain personality traits predict displaced aggressive behaviour, the uniquely longitudinal effect of indigenous interpersonal traits on displaced aggressive behaviour is ignored. To address this gap, we explored the longitudinal relationship among an indigenously interpersonal trait of China (interpersonal openness), hostile attribution bias, and self-reported displaced aggressive behaviour. Additionally, we tested whether hostile attribution bias mediated the relationship between interpersonal openness and self-reported displaced aggressive behaviour. The Interpersonal Self-Support Scale for Undergraduate Students, Word Sentence Association Paradigm for Hostility, Displaced Aggression Questionnaire, and the NEO Personality Inventory-3 were administered to 942 undergraduates on two occasions, 6 months apart. A cross-lagged model showed that, after controlling for the Big Five personality traits, interpersonal openness predicted subsequent hostile attribution bias, and hostile attribution bias predicted self-reported displaced aggressive behaviour 6 months later. Hostile attribution bias at time 2 mediated the relationship between interpersonal openness at time 1 and self-reported displaced aggressive behaviour at time 2. These results were consistent with the interpersonal self-support theory's appraisals of interpersonal openness, and they extended the social information processing and general aggression models to explain displaced aggressive behaviour.