Abstract: Objective To compare the dosimetric parameters of 4 simultaneous integrated boost intensity-modulated radiotherapy （SIB-IMRT） treatment plans with different beams. Methods Four SIB-IMRT treatment plans with different beams of 3， 5， 7 and 9 were designed for twenty-four eligible patients with cervical and upper thoracic esophageal carcinoma. PTV-G and PTV-C were defined as the GTV and CTV plus 10 mm in all directions， which were delivered simultaneously to 60.2 Gy and 56 Gy in 28 fractions， respectively. Compared and evulated the dosimetric parameters of planning target volums and organs at risk（OARs） through the DVH diagram. Results The values of conformity index （CI） and heterogeneity index （HI） of four SIB-IMRT treatment plans with different beams of 3， 5， 7 and 9 were 0.33，0.55，0.77，0.80 and 1.09，1.07，1.07，1.05 in PTV-G，with significant difference（P＜0.05）. The values of CI and HI of SIB-IMRT treatment plans with four different beams were 0.69， 0.71，0.72，0.79 and 1.22，1.13，1.075，1.073 in PTV-C，with significant difference （P＜0.05）. The values of maximal dose of spinal cord were 4511.27，4288.31， 4224.60 and 4201.43 cGy in 3，5，7，9beams SIB-IMRT plans （P＜0.05）. With increased beam numbers， the V5 increased and the V20 decreased. The 9-beams plan had significantly increased V5 and nonsignificantly decreased V20 compared to the 7-beams plan. The V5 and V20 were 44.56％ and 19.28％ in 9-beams plan and 32.36％ and 19.65％ in 7-beams plan. Conclusion 7-beams SIB-IMRT plan was the preferred technique in cervical and upper thoracic esophageal carcinoma with uniform target dose and high degree conformity， which could provide the best protection to the lung and other vital organs.