Objective To construct a mouse model of Pneumocystis pneumonia ( PCP) and evaluate the immunological characteristics of the model mice. Methods A PCP model was established by endotracheal infusion of Pneumocystis murine into severe combined immune deficiency mice. The etiology was identified by quantitative real-time PCR and silver hexaammonium staining of lung tissue. The degree of lung tissue injury was assessed by HE staining, and immunological evaluation was performed by immunofluorescence staining and flow cytometry. Results After six weeks of P. murina infection, there were significantly more lung tissue rRNA copies from P. murina in the experimental group than the sham group. P. murina trophozoites and cysts were detected in lung tissue sections from mice in the experimental group by silver hexaammonium staining. HE staining showed the alveolar walls of lung tissues in the experimental group were thickened, the lung interstitium was widened, and a large number ofGr-1⁺ neutrophils andCD68⁺ macrophages had infiltrated the lungs. The levels of myeloperoxidase, a marker of neutrophil activation, and nitric oxide synthase, a marker of macrophage activation, were significantly increased. Flow cytometry showed that the number and proportion of neutrophils and monocytes in the lungs and alveolar lavage fluid were significantly higher in the experimental group than the control and sham groups. Conclusions A stable PCP mouse model was established by endotracheal infusion of P. murina into SCID mice, which showed immunological characteristics similar to clinical signs.