Abstract: As the global population grows, food production is falling short of demand, while environmental degradation is forcing changes in traditional food supply systems. Microalgae are rich in macronutrients and bioactive substances, which can provide nutrients for the human body and have antioxidant, antibacterial, immune regulation, and other functions. As a potential new food source, microalgae are gaining increasing interest. This paper reviews the characteristics and extant edible microalgal species, as well as the physiological functions of microalgal proteins, polyunsaturated fatty acids, polysaccharides, and bioactive substances. The application potential and prospect of microalgae in replacing meat proteins, compensating for salt reduction food flavor, bacteriostasis and preservatives, and the development of functional foods are discussed in detail, as are the existing challenges in their application as food. The objective is to provide theoretical references for the development of microalgae food and the exploration of new food resources.