Objective To observe the dynamic change of immune response in mice infected with Echinococcus alveolaris(AE) at difference period of time, and to explore hostalveo’s immune regulation. Methods The infection lasted and was followed up for 25 weeks. The spleen cells from BALB/c mice infected with AE stimulated with EmAg and ConA or PHA in vitro . IL-2R, IFN-?, TNF-?, IL-1 and specific IgG subclasses were determined by ELISA. NO was tested by chemical assay. Results NO level sharply rised in 16 weeks after BALB/c mice were infected with AE. The levels of IgG1 and IgG3 significantly increased 8 weeks after infection, and remained elevating throughout the period of observation. IgG3 showed slight increase, IgG2a and IgG2b appeared low level following infection. The production of IL-2R and TNF? increased significantly 8 weeks of infection, while IL-2R sharply decreased in 12 weeks of infection. During the period of 2-12 weeks of infection there was an increase in IL-1 secreting. The level of IL-1 and TNF? rapidly increased since 16 weeks post infection. High level of IFN-? was detected during the period of observation, and showed a peak at 12 weeks. Conclusion Th1 is the major response in the early stage of infection,which is replaced by Th2 response in later period of infection.