Abstract: Objective: To retrospectively analyze the long-term curative effects and prognostic factors of 137 cases of NPC patients treated with intensity modulated radiation therapy.Method: The three-dimensional conformal intensity modulated radiation therapy adopted for the design plan of 137 cases of newly diagnosed and no distant metastatic NPC patients.Evaluation of short-term clinical efficacy was made according to the efficacy evaluation criteria of WHO solid tumor one month after radiotherapy. During the 2 years after radiotherapy, re-examinations were made every 3 months. Two years later, re-examinations were made every 6 to 12 months, and the routine examinations included clinical body check, nasopharyngoscope, CT, B Chao, MRI, chest X-ray, bone scan, so as to understand the condition of cavum nasopharyngeum, cervical lymph nodes and cranial nerves. Life table method was adopted to calculate the overall survival rate, Kaplan-Meier method was used to calculate relapse-free survival rate, distant metasis-free survival rate and disease-free survival rate. Log-rank test was used for univariate analysis of 14 clinical factors which may exert influences on prognosis. Multivariate analysis was performed with the Cox regression model,P<0.05 is of statistical significance.Result: ①Of the 137 cases, the overall survival rates of 1-year, 3-year and 5-year were 98.5%, 90.3%, 74.6% respectively, relapse-free survival rates were 97.0%, 81.9%, 66.7% respectively; distant metasis-free survival rates were 96.3%, 80.5%, 56.0% respectively; disease free survival rates were 95.6%, 76.9%, 43.8% respectively. ②Univariate analysis revealed that the influences of T-staging,N-staging, 92 Fuzhou clinical staging, combined chemotherapy, skull base bone destruction,injury of cranial nerve, retropharyngeal lymph node metastasis, residual disease, total time of IMRT on prognosis were of no statistical significance(with all the P values lower than 0.05) The influences of gender, nationality, age, pathological type and anemia or on prognosis were of no statistical significance(with all the P values higher than 0.05).③T-staging, skull base bone destruction, injury of cranial nerve, retropharyngeal lymph node metastasis, N-staging, combined chemotherapy, residual disease, total time of IMRT, and anemia were drawn into Cox model, and the results showed that N-staging, combined chemotherapy, injury of cranial nerve, residual disease, and total time of IMRT were independent factors that affect prognosis(with all P values lower than 0.05).Conclusion: IMRT obviously has advantages than conventional radiotheraphy in treating NPC patients. N-staging, injury of cranial nerve, combined chemotherapy, residual disease, and total time of IMRT are the main factors that affect prognosis.