Abstract: Objective To compare the clinical efficacy and safety of hypofractionated -simultaneous integrated boost-intensity modulated radiotherapy (HF-SIB-IMRT) and conventional radiotherapy for early-stage breast cancer patients after breast-conserving surgery. Methods From August 2015 to August 2017, 60 patients with early-stage invasive ductal breast cancer (cT1-T2N0M0 staging) underwent breast conserving surgery in a hospital were enrolled. According to the random number table method, they were divided into HF-SIB-IMRT group (30 cases) and conventional radiotherapy group (30 cases). After operation, the HF-SIB-IMRT group received total breast irradiation for 15 times, and simultaneous integrated boost of tumor bed for 24 days. The routine radiotherapy group received 25 fractions of total breast irradiation followed by sequential irradiation, and local total irradiation 60.0 Gy in the tumor bed. The total course of treatment was 44 days. The local control rate, cosmetic effect, incidence of radiation-related side effects and recurrence rate were compared between the two groups. Results Both groups were followed up for at least 1.5 years. During the follow-up period, there was no recurrence in both groups. The local control rate was 100% and the one-year survival rate was 100%. There was no significant difference in cosmetic effect between HF-SIB-IMRT group and conventional radiotherapy group at the end of 1 month,6 months (all P>0.05). There was no significant difference between HF-SIB-IMRT group and routine radiotherapy group in the incidence of acute adverse events (P>0.05). Conclusion Whole breast hypofractionated intensity modulated radiotherapy with simultaneous integrated boost of tumor bed after breast conserving surgery for early breast cancer patients can obtain satisfactory short-term curative effect, without increasing the toxicity and side effects of radiotherapy, and can shorten the total course of radiotherapy after breast conserving surgery, which is its clinical advantage.