To investigate the therapeutic effect difference and the possible reasons of different site esophageal carcinomas treatment using three-dimensional radiation therapy. From September 2003 to January 2009, 781 patients with esophageal squamous cell carcinoma received conventional fraction three-dimensional radiation therapy. Of all the patients, 31 cervical, 210 upper-thoracic, 427 middle-thoracic and 113 lower-thoracic esophageal carcinomas were included. The prescribed doses were ranged from 50-70 Gy with median dose of 60 Gy. The survival rates and prognosis factors of different site esophageal cancers were analyzed, Kaplan-Meier method was used to calculate the survival rates and Cox Regression analysis was used to find prognosis factors. The follow-up rate was 95.8%. The 1-, 3-, 5-year survival rates of cervical, upper-thoracic, middle-thoracic and lower thoracic segments were 83.9%, 67.4%, 58.1%; 80.4%, 47.4%, 35.5%; 63.7%, 30.2%, 21.9% and 69.9%, 33.6%, 28.8%, respectively. There was no significant difference between the groups of cervical and upper-thoracic segments (chi-square = 3.030, p = 0.082), middle-thoracic and lower-thoracic segments (chi-square = 1.346, p = 0.246). But the therapeutic effect of cervical segment was better than that of middle-thoracic and lower thoracic segments (chi-square = 11.639 and 7.373, p = 0.001 and 0.007), the therapeutic effect of upper-thoracic segment was also better than that of middle-thoracic and lower thoracic segments (chi-square = 17.736 and 4.408, p = 0.000 and 0.036). Patients with cervical and upper-thoracic, and middle-thoracic and lower-thoracic carcinoma were combined into two different groups, the 1-, 3-, 5-year survival rates of the two groups were 80.8%, 50.0%, 38.7%, and 65.0%, 30.9%, 23.4%, respectively (chi-square = 23.012, p = 0.000). The gross tumor volume was comparatively larger (48.22 cm3∶ 34.74 cm3, Z = 5.795, p = 0.000), the lesion was longer (5.20 cm∶ 4.80 cm, Z = 2.361, p = 0.018) and the age was elder (67∶ 63, Z = 2.816, p = 0.005) in the group of middle-thoracic and lower thoracic group. Multivariate analysis showed lesion length, the primary tumor site, N stages and gross tumor volume were independently prognosis factors(chi-square = 4.127; 10.011; 10.337; 11.194, p = 0.042; 0.002; 0.001; 0.001). The three-dimensional conformal radiation therapy effect for patients with cervical, upper-thoracic segments is better than that of middle-thoracic, lower-thoracic segments.