Abstract: Alveolar hydatids of Echinococcus multilocularis obtained from the peritoneal cavity of mice were subject to freezing at-10℃ and-30℃ respectively.After 130-200 days' storage,the alveolar hydatids were transferred into the mouse peritoneal cavity for viability and inactivity testing.It was found that the alveolar hydatids stored at-10℃ were more severely damaged than those stored at-30℃.The viability of the isolated alveococcus lasted half a year at-30℃.