Using silica gel column chromatography and recrystallization, a light yellow needle crystal with a purity of 97.21% was obtained from ethyl acetate fraction of ethanol extract from dry root of Glehnia littoralis Fr.Schmidt ex Miq.,and was identified as bergapten by means of NMR. The experimental result of antitumor activity in vitro shows that 0.01-100.00 mg·L^-1 bergapten have inhibitory effect to liver cancer cell line HEP-G2, in which inhibition of 100.00 mg·L^-1 bergapten is the highest with an inhibitory rate of 95.0%. In concentrations of 0.01-100.00 mg·L^-1,only 100.00 mg·L^-1 bergapten has an inhibitory effect to stomach cancer cell line SGC-7901 with an inhibitory rate of 79.6%.