Abstract: Objective: To investigate the relationship between primary tumor volume and clinical T staging of nasopharyngeal carcinoma (NPC),so as to provide theoretical evidences for reasonable clinical staging of NPC. Methods: Forty-three patients received CT enhanced scanning before radiotherapy. Then each layer contour of primary tumor was sketched by 3D-Doctor^tm software, volume of primary tumor was computed. Results: According to the '92 staging, the average volume for different T staging is as followed: T1 =15.99±4.20cm³, T2=29.95±6.61cm³, T3=40.62±8.11cm³ and T4=56.56±8.23cm³, respectively, having significant difference in each stage analyzed by statistics (F=37.60, P<0.01). Comparing the NPC volumes of previous(T₁+T₂) stages with that of advanced (T₃+T₄), with average values of 26.78±8.51cm³ and 45.93±11.06cm³, there is also a significant difference in statistics(t=6.38,P<0.01). There was an overlap in distribution of tumor volume in adjacent T staging. Conclusions: The '92 staging can reflect the distribution of different T staging in tumor volume of NPC on the whole. It is suggested that volume factor be listed in T staging and subdivided in current single stage, in order to differentiate prognosis making staging scientific and rational.