In this study,the eligible breast cancer patients will be randomized divided into two groups. the study group receive the accelerated hypo-fractioned whole breast irradiation with a concurrent boost to the tumor bed (WBI 2.5Gy x18 and SIB 2.88Gy x18) and the control group receive conventional fractioned whole breast irradiation with a concurrent boost to the tumor bed(WBI 1.8Gy x28 and SIB 2.15Gy x28). All radiotherapy will be delivered by external beam-intensity modulated radiotherapy. the purpose of this study is to assess whether the accelerated hypo-fractioned is non-inferior to the conventional fractionated radiotherapy. The outcomes evaluation will include acute toxicity , late toxicity including breast fibrosis and cardiac disease, cosmetic outcome ,local control and survival outcome.