Many large-scale clinical trials have confirmed that radiotherapy can significantly reduce the risk of local recurrence and mortality of breast cancer. Traditional radiotherapy has some disadvantages such as money- and time-consuming and traveling inconvenience, and the adverse reactions may cause the radiotherapy delay, which may impair the treatment effect. However, low energy hypo-fractionated radiotherapy offers solutions to those problems without impact on radiotherapy efficacy. The authors address the progress of hypo-fractionated radiotherapy for breast cancer.