〔Abstract〕 Objective To compare the dosimetry differences in target volume and associated organs at risk treated with 3-field and 5-field intensity-modulated radiation therapy (IMRT) plans for thoracic esophageal carcinoma. Methods A retrospective analysis was conducted on 281 patients with thoracic esophageal carcinoma admitted to Quanzhou Guangqian Hospital from September 2019 to August 2020. They were divided into two groups according to different treatment regimens: 3-field group (146 cases) and 5-field group (135 cases). Patients in the 3-field group were given a 3-field intensity-modulated plan, while those in the 5-field group were given a 5-field intensity-modulated plan. The dosimetry differences in target volume and organs at risk between the two treatment plans were compared. Results There was no significant differences in D_max, D_min and D_mean between the intensity-modulated plans on planning target volume (PTV)1 and PTV2 (P > 0.05). The D₉₅, V_95% and CI with 5-field IMRT were higher than those of 3-field IMRT, and the HI was lower than that of 3-field IMRT, the differences were statistically significant (P < 0.05). Moreover, the V₅, V₂₀ and V₃₀ of the right and left lungs of the 5-field IMRT were higher than those of 3-field IMRT, and the differences were statistically significant (P < 0.05). Conclusion The conformity of target volume with 5-field IMRT plan performs is much higher than that of 3-field, which has certain advantages in application among most patients.