Astaxanthin has extraordinary antioxidant activity. However， there is a large gap between the chemical synthesis and natural astaxanthin in terms of function and safety. Therefore， the extraction of astaxanthin from natural biological resources has become the dominant market demand. At present， traditional methods for extracting natural astaxanthin has the disadvantages of high temperature and time-consuming， which is not conducive to maintaining the stability of the structure and function of astaxanthin. In this study， microemulsion systems with high biocompatibility were constructed at near room temperature with tetrabutylphosphonium trifluoroacetate （[P4444]CF3COO） or tributyloctylphosphonium bromide （[P4448]Br） as non-polar phase， lecithin and n-butanol as compound surfactants， and water as polar phase. Natural astaxanthin was extracted from Antarctic krill by the microemulsions. When the ultrasonic extraction time and power were 2 min and 100 W， respectively， the extraction yield of astaxanthin by using [P4444]CF3COO/lecithin/n-butanol/water （mass ratio = 0.2 ∶ 0.12 ∶ 0.48 ∶ 0.2） reached （48.21±0.07）μg/g （97.75%）. The results have shown that the ionic-liquid-based microemulsion containing lecithin is beneficial to improve the solubility of hydrophobic molecules， and is an alternative solvent system to organic reagents. This study provides a new method for the extraction of natural astaxanthin.