Objective To establish an swine influenza virus (H9N2) infection model in BALB/c mice and to provide animal models for studying its pathogenetic mechanism. Methods Eighty mice were divided into experimental and control groups, 40 in each group. The experimental mice were infected with swine influenza virus (H9N2) by nose dropping. Then the clinical symptoms and histopathological and ultrastructural changes were observed. ResultsThe BALB/c mice showed clear clinical symptoms and typical pathological lesions. Conclusion A BALB/c mouse model of swine influenza virus (H9N2) infection has been successfully established.