This study was designed to explore how supercritical fluid CO2 extract of Ligusticum chuanxiong Hort (CX) protects mouse liver and kidney from D-galactose-induced injury. The antioxidant capacity of CX was confirmed both in vitro and in vivo. The D-galactose-induced malondialdehyde increase was attenuated by CX, as well as the increase in aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine level. In addition, the activities of antioxidant enzymes were markedly renewed, and the gene expressions of these enzymes were upregulated in CX groups. The results of histological analysis suggested that CX could effectively attenuate the D-galactose-induced structure damage. Furthermore, results of Western blotting analysis showed that CX significantly inhibited the upregulation of nuclear factor protein expression caused by D-galactose. In conclusion, CX could attenuate the liver and kidney injury in D-galactose-treated mice, and the mechanism might be associated with attenuating oxidative stress and inflammatory response.