Cognitive behavioral theory emphasizes the significant role of mental imagery in the onset and development of Social Anxiety Disorder (SAD). However, the neural mechanisms underlying the generation of social scenario imagery in individuals with social anxiety remain unclear. In this study, 28 individuals with social anxiety and 31 healthy controls performed a retrospective cue imagery generation task to examine their neural responses. Behavioral results showed that, compared to negative social scenarios, the vividness of positive social scenario imagery was significantly lower in the social anxiety group, while the control group showed no significant difference between the two conditions. Event-related potential (ERP) results revealed that, for the social anxiety group, N170 and LPP amplitudes were significantly larger under the neutral condition compared to the negative condition, whereas the control group exhibited no significant difference between these conditions. Furthermore, the social anxiety group showed significantly larger LPP amplitudes than the control group in both the positive and neutral conditions. These findings provide the first neurophysiological evidence that individuals with social anxiety exhibit processing biases when generating imagery of positive and neutral social scenarios, suggesting heightened neural engagement in these conditions.