Natural astaxanthin usually comes from three biological sources: waste from aquatic product processing industry, Phaffia rhodozyma and microalgae (Haematococcus pluvialis). Among them, the content of astaxanthin in waste is low and the extraction cost is high, which is not suitable for large-scale production. The average content of astaxanthin in natural rhodozyma is only 0.40%. In contrast, the content of astaxanthin in Haematococcus pluvialis is 1.5% ~ 3.0%, which is regarded as the "concentrate" of natural astaxanthin. [1] A large number of studies show that Haematococcus pluvialis has a higher accumulation rate and total output of astaxanthin than other green algae, and the ratio of astaxanthin and its esters (about 70% monoester, 25% diester and 5% monomer) contained in Haematococcus pluvialis is very similar to that of aquaculture animals, which is an advantage that chemical synthesis method and astaxanthin extracted by Rhodotorula do not have. In addition, the structure of astaxanthin in Haematococcus pluvialis is mainly 3S-3, which is basically the same as that in aquatic organisms such as salmon. The astaxanthin structure in Phaffia rhodozyma is 3 R-3R type. At present, Haematococcus pluvialis is recognized by nature as the best organism to produce natural astaxanthin. Therefore, the extraction of astaxanthin from this microalgae undoubtedly has broad development prospects and has become a research hotspot in the production of natural astaxanthin in the world.