Harmful algal blooms (HABs) pose a serious threaten to water environment because of the released toxic substances and dramatic underwater light reduction. How to control HABs is attractive and has attracted worldwide attentions. Among them, microorganisms show great application potential in prevention and control of HABs because of the fast growth, easy propagation and rapid metabolism. Here, we summarized the distribution and diversity of isolated algicidal bacteria and the underlying algicidal mechanisms (algicidal mode, cell morphology, photosynthesis, and oxidative damage).