The present invention relates to a composition comprising Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof as an effective ingredient. Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof of the present invention is highly effective for the improvement of liver functions since it can lower the level of GOT, GPT, ALP, BUN and total bilirubin, which are major liver function indices. ALP and BUN are also used as kidney function indices, so the decrease of the level of ALP and BUN by the extract of the present invention indicates that Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof of the invention can improve kidney functions as well. Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof of the present invention also can lower the amount of hydroxyproline in liver but increase the amount of hydroxyproline in kidney, suggesting that the extract above has excellent anti-fibrosis and kidney protecting effects. In addition, Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof of the present invention can lower the level of malondialdehyde, an index of lipid peroxidation in liver and kidney tissues, suggesting that the extract has excellent anti-oxidative effect. Hovenia dulcis Thunb extract, Lindera obtusiloba extract or herbal mixture extract thereof of the present invention promotes cell viability in liver and kidney cell lines, indicating that the extract has excellent liver and kidney cell protective effects. Therefore, the composition of the present invention can be effectively used not only for anti-oxidation and anti-fibrosis but also for the protection and the improvement of liver and kidney functions.