Objectives: The present study aimed to conduct a comprehensive study examining stigma towards mainstream students with Autism Spectrum Disorder (ASD) in local pre-service teachers. The study assessed the contributory role of both illness-related predictors (knowledge of ASD and threatening illness perceptions) and personal prosocial traits (the need for closure (NFC), compassion, psychological inflexibility) in stigma formation. Research effort has also been paid to investigate how stigma affected emotional and behavioural consequences in this particular context. Methods: 133 education-majoring local students (mean age = 20.89, 81.2% female) responded to the study by completing a questionnaire, which consisted of a battery of psychological scales measuring different constructs. Results: All five predictors and three consequences were found significantly correlated to stigma. Compassion and psychological inflexibility demonstrated an extra explanatory power on stigma formation after controlling the effect of the two illness-related predictors. A partial mediating effect of negative affect was also observed between stigma and punitive intention. Conclusion: Personal traits exert an influence on stigma formation, further examination of relevant interventions and meditations deserve future research effort. The partial mediating effect of negative affect provides an insight to help understand the mechanism from stigma to teaching-related behaviours. All rights reserved.