Objective To compare dosimetry between volumetric modulated arc therapy （RapidArc） and nine-field fixed-gantry dynamic intensity-modulated radiotherapy（dIMRT） for nasal natural killer/T-cell lymphoma． Methods RapidArc and dIMRT plans were generated for 10 patients with natural killer/T-cell lymphoma based on the Varian Eclipse 8.6 radiation treatment planning system. Planning target volume （PTV） and organs at risk（OAR） were evaluated using dose-volume histograms （DVHs）. Results  Compared to RapidArc， the dIMRT approach showed higher Dmin for PTV （3.48 Gy，t=-3.810，P=0.004），lower Dmax for PTV （2.12 Gy，t=3.979，P=0.003），lower Dmean for PTV（1.65 Gy，t=4.933，P=0.001），superior homogeneity index（t=5.068，P=0.001），and similar conformity index. In addition，the dIMRT approach was associated with lower values of Dmax for the right optic nerve（0.75 Gy，t=3.266，P=0.010），Dmean for the right eyeball（2.24 Gy，t=2.351，P=0.043），Dmax for the spinal cord （1.92 Gy，t=2.828，P=0.020），Dmean for spinal cord （0.46 Gy，t=3.497，P=0.007）and Dmean for the left parotid（1.45 Gy，t=3.483，P=0.007）. Conclusions Both RapidArc and dIMRT plans satisfied clinical requirements，but dIMRT plans were associated with superior homogeneity index， better protection of some OARs as well as greater monitor unit.