As the world’s largest agricultural producer，China’s long-term agricultural production mode relying on chemical fertilizer inputs has triggered a series of serious ecological and environmental problems. It has not only led to the excessive consumption of resources such as nitrogen and phosphorus，but also caused the problems of soil quality degradation，crop yield reduction，and the aggravation of environmental pollution，and even posed a threat to the public health of human beings. Microalgae bio-fertilizer has become a new type of functional fertilizer with broad prospects due to the advantages of its wide range of raw materials，rich nutrients and diverse active substances. This paper systematically reviewed the classification system of microalgae biofertilizers，the mechanism of crop growth promotion，the mechanism of resistance enhancement and the mechanism of soil improvement，aiming to provide theoretical support and practical guidance for the diversified application of microalgae biofertilizers in the sustainable development of agriculture.