Abstract: This paper reports on the results of the scolicidal action of three species of Corydalis(C. sibirica Maxim, C. boweri Hemsl, C. lineariodes Maxim) from Qinghai Plateau against E. granulosus protoscolices in vitro. The water and ethanol extracts of C. sibirica and their total alkaloids, the water extracts of C. boweri and d-adlumine of C. lineariodes all had stronger scolicidal action than H2O2 against protoscolices as judged by their loss of motility, readiness to take vital stains and inabilitty to develop into secondary hydatid cysts after being inoculated into albino mice. The total disintegration of protoscolices by both the total alkaloides of C. sibirica and d-adlumine through formation of "tegumental bubbles" and disruption of the external plasma membrane was demonstrated by scanning electron microscopy.It is suggested that the alkaloid of Corydalis might be a promising drug for local use in hydatid surgery.