Soil is the basis of agriculturalproduction，and its quality directly affects the quality and yield of crops.Microalgae，being rich in resource，is an important component of soil microorganisms，and has the functions of nitrogenfixation，carbon fixation and secretion of plant growth hormones.It has good effects in promoting crop growth，improvingsoil fertility and soil structure.In this paper，the advantages of microalgae as bio -fertilizer，the application of microalgae bio-fertilizer in agricultural production and agro-ecological protection，and the development of new technologies in recentyears，the status of commercialization and the development direction in future were summarized，and it can provide a scientific theoretical basis for the application of microalgae bio-fertilizer.