Abstract: Due to human activities and global warming, diatom blooms occur frequently, causing negative impacts on aquatic ecology and water supply. Series of studies on freshwater diatom blooms have been published, but there is a lack of summary of their causes and control methods. The key factors for freshwater diatom blooms include temperature, light, nutrients and flow rate. In terms of in-situ prevention, water scheduling and water aeration are well established and have higher control efficiency for diatom blooms. However, chemical technology treatments and biological strategies are not satisfied due to environmental limitation. For water plant control, it is efficient to remove diatoms through a combination of coagulants and coagulant aids or oxidants. The expansion of the diatom blooms will make it difficult to adjust the treatment process in time and affect the water production efficiency. It is of very important to understand the causes and control methods of freshwater diatom blooms to further ensure the safety of drinking water.