Abstract: Objective To study the clinical curative effect and adverse reaction of the nasal NK/T cell lymphoma treated by tomotherapy. Methods Of the 25 cases with nasal NK/T cell lymphoma treated by tomotherapy in our hospital from August 2008 to April 2013, three patients had no chemotherapy, 1 case underwent concurrent chemotherapy and radiotherapy, 2 cases underwent sequential chemotherapy after radiotherapy, the rest of the patients were performed 1-2 sequential chemotherapy cycle induction chemotherapy after radiotherapy. All patients were given priority to CHOP-L scheme chemotherapy, with the total chemotherapy cycles of 1-7 times and the median cycles of chemotherapy for 4 times. Tomotherapy were performed in patients with the GTV DT of 50 - 56 Gy (median dose 50 Gy) and the single dose of 2 - 2.78 Gy, CTV DT of 36 - 50 Gy (median dose 40 Gy) and the single dose of 1.6 - 2 Gy. Results Of all the 25 patients after radiotherapy, 14 cases reached to CR, 4 cases reached to PR, 3 cases reached to PD, 2 cases lost of follow-up, 2 patients died within a month after radiotherapy. The total effective rate of (CR + PR) was 78.3%, and the total 2 years survival rate was 92% with the average survival period of 55.3 months (95% CI: 49.0 to 61.5 months). Different degree of dry mouth and taste change symptoms occurred in most patients after radiotherapy, with vision or hearing loss in a small number of patients and brain damage symptoms in no patients. Conclusion Better clinical effect and lower side reaction are observed in nasal NK/T cell lymphoma patients treated with tomotherapy.