In order to improve diagnostic method to Babesia gibsoni infection,gene recombination technique was used in our study.By this technique,we constructed and expressed recombinant apical membrane antigen-1(BgAMA-1),and recombinant BgAMA-1 was used in ELISA experiment as diagnostic antigen.The results showed the recombinant expressed plasmid was triumphantly constructed and the recombinant antigen BgAMA-1 had a high specificity in ELISA test.These results demonstrate that the recombinant BgAMA-1 might be a useful diagnostic reagent for detection of antibodies to B.gibsoni in dogs.