The invention provides a recombinant antigen protein rP44-60 for detecting granulocytoplasmosis and a kit containing the antigen, and belongs to the technical field of immunology, and the recombinant antigen protein comprises an amino acid sequence as shown in SEQ ID NO.1 in a sequence table. The kit comprises a recombinant antigen protein rP44-60, a sample pad, a combination pad, an absorption pad, a nitrocellulose membrane, a colloidal gold probe, mouse IgG and goat anti-mouse IgG. The recombinant antigen protein disclosed by the invention is high in sensitivity and strong in specificity, and can be used for rapidly detecting an antibody in anaplasma phagocytophilum infected serum, so that the problem that the antibody is difficult to capture due to antigen variation of HGA is solved, the defect of existing antigen missing detection is made up, and the missed diagnosis rate is effectively reduced; according to the preparation method, cross reactivity caused by irrelevant sequences is reduced, and the expression quantity and stability of recombinant antigen protein are high; the kit has the characteristics of rapidness, sensitivity, high specificity, no limitation of experimental conditions and the like, and has low requirements on detection conditions.