Glycyrrhizic acid (GA), the main component from Radix glycyrrihizae, has a variety of pharmacological actions. In present study, GA nanoparticles suspension was prepared by supercritical anti-solvent (SAS) process and high-press homogenization process, and comparative studies were done on oral bioavailability, hepatic function and liver antioxidative activities in carbon tetrachloride–induced liver damage rats after treated with GA nanosuspension and unprocessed GA solution. Micronized CA under the optimum SAS conditions and CA nanosuspension prepared by high-pressure homogenization with the average particle size of about 80nm were obtained. GA nanoparticles suspension, compared with the unprocessed GA can significantly enhance the oral bioavailability. For carbon tetrachloride–induced liver damage rats, GA nanoparticles suspension can significantly reduce the release of ALTand AST. The plasma ALT and AST levels of GA supplementation were effective in decreasing up to 55 and 78.6 percent of model control group, respectively. For the GA solution group, the plasma ALT and AST levels were in decreasing up to 62.8 and 84.5 percent of model control group, respectively. GA nanosuspension could also significantly reduce plasma MDA and enhance SOD, GSH-Px and CAT activity. The CAT, SOD and GSH-Px activities increased by GA nanosuspension were about 1.31-fold, 1.43-fold and 1.28-fold of the unprocessed GA solution group, respectively. These results indicated that the GA nanoparticles suspension can be absorbed more easily than unprocessed GA after oral administration.