Abstract: Objective: To explore the relationship among left-behind experience, social anxiety, mindfulness level and alexithymia of college freshmen.Methods: A total of 2, 341 freshmen (723 with stay-behind experience and 1, 618 without stay-behind experience) were selected from a medical university in Guangdong Province.The investigation was conducted using self-designed demographic and stay-behind experience questionnaire, Mindful-ness Attention Awareness Scale (MAAS), Alexithymia Scale (TAS-20) and Social Anxiety Scale (IAS).AMOS 24.0 was used to construct the structural equation model.Results: The scores of TAS-20 and IAS of freshmen with stay-behind experience were higher than those of freshmen without stay-behind experience, and the score of MAAS was lower than that of freshmen without stay-behind experience (P< 0.01).MAAS score of freshmen was negatively correlated with TAS-20 score and IAS score (r=-0.647, r=-0.350, P< 0.01).TAS-20 score was positively correlated with IAS score (r=0.338, P< 0.01).The direct effect of left-behind experience on social anxiety was not significant.The relationship between left-behind experience and social anxiety was affected by the indirect effects of mindfulness level (effect size: 0.022, effect ratio: 44%), alexithymia (effect size: 0.009, effect ratio: 18%), and the chain mediating effect between the mindfulness level and alexithymia (effect size: 0.019, ef-fect ratio: 38%).Conclusion: Left-behind experience may influence social anxiety through the mediating effect of mindfulness level, alexithymia, and the chain mediating effect of mindfulness level and alexithymia.