Abstract: Objective To assess the psychological characteristic of EORTC QLQ-C30 scale;and to measure whether QLQ-C30 scale was suitable to measure the QOL of nasopharyngeal carcinoma(NPC) patients. Methods The data of 391 NPC patients from Cancer Hospital of Sun Yat-Sen University were collected.The reliability,validity and discrimination of scale were assessed by reliability and validity theory.And differential item functioning(DIF) was reviewed by item response theory evaluation. ResultsCronbach′s α coefficients of QLQ-C30 domains were greater than 0.7,except physical function and cognitive function domain.Split-half reliability of QLQ-C30 domains was greater than 0.7,except physical function domain and fatigue.Test-retest coefficients of QLQ-C30 domains were greater than 0.7.The result of factor analysis showed that the data were consistent with the theoretical model.Most of the domain scores and dimension scores of patients in different radiotherapy stages were significantly different(P<0.05).All the items had not uniform or non-uniform DIF between different gender and age groups. Conclusion QLQ-C30 scale was a reliable and valid disease-specific instrument,with good receptiveness to evaluate QOL of NPC patients.