To study the anti-cancer activity of the three anti-oncoprotein p185 mAbs established by surface epitope masking method so as to provide some basic information for clinical tumor targeting therapy.Methods: Immnune flurorence staining, MTT assay, soft-ar-gar culture and long-term cell proliferation assay detected the suppressive activities of the mAbs against the breast cancer cells overexpressing p185 and p185-transfected fibroblast cells, and the inducing effects of the mAbs on tumors sensitivity to chemotherapy.Results:The 3 mAbs specifically suppressed tumor cell proliferation and enhanced the sensitivity of tumors to chemotherapeutics. Conclusion:These mAbs have the potentials to develop into the clinical tumor targeting therapeutic reagents of the tumors overexpressing p185.