Objective: To explore the relationship between extended mind and nomophobia, as well as the moderating effect of mindfulness. Methods: 750 college students were investigated with Extended Mind Questionnaire , Nomophobia Scale for Chinese and Child and Adolescent Mindfulness Measure. Results: There is a significant positive correlation between extended mind and nomophobia (r=0.59, p<0.001), and significantly positively predicted nomophobia (β=0.47, p<0.001), mindfulness was negatively correlated with nomophobia, and significantly negatively predicted nomophobia( β=-0.11, p<0.05); Mindfulness plays a mediating role between extended mind and nomophobia (effect value is -0.28). Specifically, when the level of mindfulness is low, extended mind predicts nomophobia more strongly (β=0.37, p<0.001), and when the level of mindfulness is high, extended mind predicts nomophobia more strongly ( β=0.12, p<0.001). Conclusion: College students who use smartphones as their own extensions of their minds are prone to nomophobia, and mindfulness can alleviate the nomophobia caused by extending their minds.