Based on the determination of wall breaking method and dissolving reagent, ultrasonic-assisted extraction was used in this study to explore the effect of extracting astaxanthin from Haematococcus pluvialis under different conditions, and further optimize the test results by response surface methodology. The results showed that under the conditions of ultrasonic time of 18 mins, ultrasonic temperature of 39 ℃, liquid-material ratio of 9∶50 (mL/mg), and ultrasonic power of 200 W, ultrasonic treatment was carried out under the condition of oscillating ultrasound. Finally, the treatment was carried out under the condition of water bath oscillation at 40 ℃ for 20 mins, the astaxanthin extraction rate can be 85.1% using Liquid nitrogen grinding broken wall treatment with ethyl acetate-ethanol (v/v: 1∶2) as the extraction solvent.