The study aimed to compare the dosimetric parameters to target dose coverage and the critical structures in the treatment planning of helical tomotherapy (TOMO), volumetric-modulated arc therapy (VMAT), and fixed-field intensity-modulated radiotherapy (IMRT) for NSCLC delivering conventionally fractionated radiotherapy. Thirty patients with pathologically confirmed NSCLC were included. Three radiation treatment plans were designed for each patient. All patients received the uniform prescription dose of 60 Gy to the planning target volume. The conformity index (CI), heterogeneity index (HI), and parameters of critical structures were calculated. A significantly superior mean CI was observed in VMAT than in TOMO or IMRT (P = 0.013, 0.001). Mean HI was also better using VAMT or IMRT than TOMO (P = 0.002, 0.003). Mean lung V-20 and V-30 were significantly reduced by TOMO compared to IMRT (P = 0.019, 0.029). The heart was spared by IMRT compared to TOMO in terms of mean heart dose, V-5, V-10, and V-20 (P < 0.05). In larger tumor, VMAT provided the optimal dose distribution and sparing to heart. Compared to TOMO and IMRT, VMAT achieved better target dose distribution and similar sparing of critical structures. VMAT seemed to be the optimal technique for NSCLC.