Abstract: OBJECTIVE To establish an animal model of human non-small cell lung cancer with brain metastases by internal carotid artery injection of PC-9 cells. METHODS PC-9 cells(2.0×10⁵·mL^-1) 100 μL on logarithmic phase were injected into 7 nude mice by internal carotid artery. The statuses of nude mice were observed after implantation. MRI scanning and HE staining were performed to investigate the metastatic lesion in brain in day 24^th after implantation. RESULTS After implantation 14 d, mice showed signs of dyscrasia gradually, including lose weight, slacking, hypersomnia, roachback and so on. MRI revealed a mass in 5 mice, and histopathologic examination with HE staining showed metastatic lesions in the brain. The rate of brain metastases of lung cancer was 71%. CONCLUSION An animal model of non-small cell lung cancer with brain metastases can be established by internal carotid artery injection of PC-9, which has advantages of simple technique, short experiment period and high success rate. MRI scaning can measure metastatic lesious in brain of nude mice, but its accuracy and darity still need to be further improved.