<p>Facial attractiveness can induce different emotional experiences, thus influencing others to make positive or negative trait inferences. However, existing studies focus on the single-face evaluations while neglecting the influence of background facial attractiveness. In this study, an implicit priming paradigm with ERP (Event-related potential) was used to investigate the influence of background faces with different levels of attractiveness on trait inference of target faces, and the role of emotion. The results show that regardless of the attractiveness of the background faces, the proportion of participants who perceived the target faces as matching positive words was higher, and the positive words induced smaller N400, indicating that the trait inference of the target faces became more positive, and there was less semantic conflict with the positive traits. Notably, distinction between positive and negative trait associations was more pronounced when target faces were presented with low attractiveness background faces compared to high attractiveness backgrounds, suggesting a stronger influence of low attractiveness contexts on trait inference. Furthermore, face pairs in the low attractiveness background condition elicited larger late positive potential (LPP) amplitudes, indicating enhanced emotional processing. These findings demonstrate that background facial attractiveness positively influences trait inferences, with emotion playing a crucial role. This study provides novel insights into the dynamics of facial trait inference in paired presentations, advancing our understanding of interpersonal perception mechanisms.</p>