The behavior of cracks and its hazards to concrete dams are common attention projects in dam engineering fields. The research progresses of behavior and hazards of cracks in concrete dams was reviewed from the four aspects, i.e., evolution rule of cracks, abnormality diagnosis of cracks, service status monitoring model of dams with cracks, and analysis methods of cracks hazards to concrete dams. The present research level was analyzed and commented. Some problems that need further research related to this subject were also pointed out.