Abstract: Objective To provide a reference for searching more optimal radiatitherapy technology through dosimetric comparison among 2D-RT，3D-CRT and IMRT plan. MethodsForty cases of middle or low thoracic esophageal carcinoma were designed 2D-RT， 3D-CRT， 5 fields and 9 fields IMRT plans for each patient in 3D planning system，and evaluated dosimetric parameters of each treatment plan with dose volume histogram and irradiation volume of normal tissues. ResultsThe CI in 2D-RT， 3D-CRT， 5 fields and 9 fields IMRT plan were 0.17±0.08，0.53±0.09，0.78±0.05，0.87±0.05，respectively（P＜0.05）；the HI value in four plans were 1.48±0.34，1.14±0.05，1.13±0.03，1.09±0.02， respectively. The HI value in IMRT was lowest，followed by that in 3D-CRT，and that in 2D-RT plan was highest. V20 and V30 of lung，the maximum dose of spinal cord and the mean dose，V40 of heart in IMRT plan were lower than those in 3D-CRT and 2D-RT plans（P＜0.05）. V5 of lung in 9 fields IMRT plan was higher than that in 5 fields IMRT plan（P＜0.05）. Conclusion The CI and HI of target area dose in IMRT plan are superior to those in 2D-RT and 3D-CRT plan. Compared to 5 fields IMRT plan， V5 of lung can be increased by 9 fields IMRT plan，and the 9 fields IMRT plan did not bring obvious improvement in dosimetry.