Abstract: This paper reports on the effect of C. sibirica Maxim on secondary Echinococcus granulosus cysts in mice. The alcohol extract, water extract and total alkaloids of the plant all inhibit the cysts development of E. granulosus in mice when administered intra-peritoneally or orally.C.sibirica Maxim caused a reduction of cyst weight from 67.0 to 85.2% compared with that of controls, and the agglutination litres of specific antibodies in the treated mice were lower than those in the controls. Bubble lesions, plaque denudation, crater-shaped pits, reduced or disappeared microtriches on the surface of cysts were observed using scanning electron microscopy. Dilated and ruptured aggregates of mieroiubules, decreased density and swelling of mitochondria and the degranulation were watched using transmission electron microscopy. The authors consider that C. sibirica Maxim may be an active drug against secondary cyst of E. granulosus in mice.