Uric acid is made from the breakdown of hypoxanthine and xanthine by enzymatic activity of xanthine oxidase (XO). The high level of uric acid in human body leads to formation of gout. Nowadays, the synthetic chemical drugs such as allopurinol is used to treat gout. However, allopurinol has many side effects. Accordingly, the alternative natural drugs of gout is introduced to be choice of treatment for reducing side effect of chemical drugs. In this study, we demonstrated Apium graveolens L. had a potent natural inhibitor to XO activity. The Apium graveolens L. was extracted by difference extraction solvents including water, methanol and 95% ethanol. The preliminary phytochemical screening revealed that all crude extracts contained steroids, tannins, saponins and alkaloids without terpenoids. At the concentration level was 100 ug/ml, all crude extract had the inhibitory activity more than 80%. IC50 value was calculated by using non-linear regression equation. The ethanolic crude extract was exhibited the highest activity with IC50 of 1.65±0.46 ug/ml, followed by methanolic and water crude extract with IC50 of 6.91±0.85 and 33.58±3.65 ug/ml, respectively. A phamacokinetic study found that Apium graveolens L. might be a therapeutic use in traditional folk medicine against xanthine oxidase-related diseases, in particular, gout.