Screening has been always considered as a double-edged sword. Cancer screening could save lives in some cases, however, in other cases, it might also turn people into overdiagnosis. Overdiagnosis is the diagnosis of cancer that will never cause symptoms or death during a patient's lifetime. Therefore, overdiagnosis might lead to unnecessary treatments and lifetime surveillance, and then increase economic burden and psychological burden. In this review, we focus on how to correctly evaluate the overdiagnosis rate, and how to avoid or reduce the harms caused by overdiagnosis in the future according to the reasons associated with overdiagnosis. After systematically reviewing the previous studies, we will try to identify the potential reasons associated with overdiagnosis in breast cancer screening with mammography, address how to correctly evaluate the overdiagnosis rate, and finally provide some suggestions to reduce the overdiagnosis.