The object of this study is to find an inhibitor on soluble epoxide hydrolase (sEH) from natural plant. Five flavonoids were isolated from Inula britannica flowers. Their structures were elucidated by analyzing NMR and Mass spectra. In vitro, the isolated compounds 1–5 were tested their inhibitory activity on sEH ranging of 3.1–100 µM. Among them, compound 3 had the IC⁵⁰ values of 12.1±0.1 µM. Based on enzyme kinetics study, inhibitors were revealed to be bound with enzyme as non-competitive type. Molecular docking study showed that 1–5 bound with the residues. Finally, these results suggest that patuletin (3) represent potentially therapeutic inhibitors of sEH.