Objectives <p>There is an increasing demand for psychometrically sound and contextually valid measurement instruments, such as the 7-item Nonattachment Scale (NAS-7), to facilitate the advancement of research on nonattachment within the Chinese cultural context. This study aimed to examine the psychometric properties of the Chinese version of NAS-7 and constructed a mediation model with cognitive flexibility as the mediating variable to explore the mechanism of nonattachment affecting mental health.</p> Method <p>The Chinese version of NAS-7 was developed through a process of Translation-back Translation, cultural adaptation, and pre-investigation. Study 1 recruited 1023 participants through online surveys and experimental platforms. Exploratory factor analysis, confirmatory factor analysis, item analysis, convergent validity analysis, and reliability analysis were performed on the translated NAS-7. Study 2 recruited 916 participants online who completed self-reported measures of nonattachment, cognitive flexibility, life satisfaction, trust, depression, anxiety, and stress.</p> Results <p>Study 1 demonstrated excellent psychometric properties of the Chinese version of NAS-7 in a sample of Chinese adults. The results of Study 2 indicated that cognitive flexibility mediated the relationships between nonattachment and life satisfaction, depression, anxiety, and stress, but not nonattachment and trust.</p> Conclusions <p>This study provided a reliable measurement tool for studying nonattachment in the Chinese context. Additionally, the current study also provided preliminary evidence suggesting that cognitive flexibility may serve as a potential mechanism underlying the effects of nonattachment on mental health.</p>