Objective To make pathological observation of MMTV Wnt 1 transgenic mice with mammary tumor.Methods The mammary tumor of MMTV Wnt 1 transgenic mice was observed and the tumor tissue was transfered to nude mouse in site to check the pathological changes .Results Tumorgenesis occurred in spleen and liver while no obvious lesion appeared in other organs. No metastasis occurred at the time mammary tumors were detected.Transplanted tumors were with the similar biological features of primar tumor.Conclusion The MMTV Wnt 1 transgenie mice conld be an animal model with mammary tumor.