Microalgae have been considered as promising candidates in integrating CO2 mitigation, nutrients degradation in water systems, and energy capture from sunlight. Therefore, it is important for sustainable development via acceleration of microalgae research to address the problems of environmental pollution and energy shortage. However, high cost in biomass recovery is the major bottleneck in microalgal-based industrial applications, and a cost-effective method in microalgal biomass recovery is the key to this issue. Here, we reviewed the methods for microalgae harvesting, including sedimentation, centrifugation, filtration and flocculation. Among these methods, the progress and prospect in flocculation are especially focused so that to propose options for the cost-effective biomass recovery and microalgal industrialization.