Abstract: An monoclonal antibody(EASP-3G3) produced previously against Eimeria acervulina sporozoites was used as tool to detect common antigen both on duodenum epithelium and sporozoites. The weight of soluble antigen recognized by MAb were determined by Western blot analysis. Immuno histochemistry and immunofluorescence techniques were used to determine whether common epitopes exist on sporozoites and duodenum epithelium The results showed that the anti-sporozoites MAb was found to react specifically with duodenum epithelium，in addition to the other parts of the digestive tract. In Western blot after sodium dodecyl sulfatepolyacrylamide gel electrophoresis，the monoclonal antibody recognized an 35-48 ku protein The results above suggested that the interrelationship between specific site invaded by Eimeria acervulina sporozoites and certain antigen existed on the surface of duodenum epithelium, can exist during the infection.