Abstract: Spirulina (Arthrospira) is the largest microalgal product by tonnage and value. There are roughly 90% of Spirulina powder and tablets is sold as human nutritional supplements. Spirulina is recognized as a superfood growingly among people, and the mechanism beyond the functional phenomena is also ongoing researching. The relationship between recommended daily intake (RDI, 3 g/d) of Spirulina and recommended nutrition intake (RNI) or adequate intake (AI) is analyzed, and the Spirulina is a good supplement for premier protein, iron, vitamin A, vitamin B₁₂, vitamin K₁ and K₂. Spirulina is also an effective supplement for manganese and iodine elements. This paper also briefly reviews the progress in the medical and pharmaceutical functions to human beings of Spirulina powder. The clinical trials show that Spirulina is a proficient nutraceuticals in controlling hypertension, diabetes, obese, etc. Finally, the progress of the application of Spirulina in food industry is also discussed. For the heat and light sensitivity of phycocyanin and chlorophyll, there is an urgent demand for the solution of stable Spirulina and new derivatives.