It is easy to increase the chemical composition of microalgae by changing the environmental conditions and other factors. Many studies indicate that the composition, including lipid content, of microalgae is closely related to the environmental conditions and medium composition. Improving the lipid content in microalgae is a focus of commercial production of mi­croalgae biomass. Current studies on high lipid content of microalgae are focused mainly on selection of microalgae species, genetic modification of microalgae, nutrient management, metabolic pathways, cultivation con­ditions, and so on.