Cognitive fusion underlies psychological inflexibility and an attempt to change consequences of undesirable thoughts and other personal events, rather than changing position. The aim of the present study was to investigate the validity and reliability of Cognitive Fusion Questionnaire, among students of Shahid Chamran University of Ahvaz. The subjects consisted 151 of university students from different disciplines who were selected through multistage cluster sampling. Study tools included Gillanders & et al Cognition Fusion Questionnaire and Nolen-Hoeksema Rumination Questionnaire. Findings showed that reliability of scale with internal consistency (Cronbach’s alpha) equals to 0.89, indicating high reliability of this scale. Concurrent validity with rumination was equal to 0.55 that illustrates concurrent validity of this scale. The results of this study showed that the 13-item cognitive fusion questionnaire’s validity and reliability is sufficient among students, and can be used in the field of clinical interventions.