In order to broaden the application of biomass materials in the field of oil-water separation，a kind of superhydrophobic stem fiber/chitosan composite aerogel was synthesized by a simple freeze-drying-normal temperature impregnation method using a large amount of cheap sunflower stems in Xinjiang as raw materials，chitosan as composite material，and stearic acid as hydrophobic modifier. The aerogel was characterized by FT-IR，SEM，and static water contact angle measuring instrument，and oil absorption and recycling performance were evaluated. The results showed that when the mass ratio of sunflower stem fiber and chitosan was 6∶1，the stearic acid dosage was 1.64%，and the immersion time was 2.5 h，the static water contact angle of the obtained composite aerogel was the largest，being of 150.9°. The adsorption capacity of the composite aerogel to different oils such as kerosene was 12.34—21.85 g/g，moreover，it still maintained stable oil absorption and hydrophobicity after 10 cycles of use. The research not only provides a new method for the preparation of oil-water separation materials，but also broadens the way for the high value utilization of abundant straw in Xinjiang.