Abstract: OBJECTIVE To analyze the effect of MMP-9 and TNF-α after pulmonary infection in patients with carotid artery atherosclerotic cerebral infarction, so as to provide references for clinical researches. METHODS A total of 120 patients with carotid artery atherosclerotic cerebral infarction from Jan.2012 to Aug.2015 were selected, and divided into infection group and non-infection group according to whether occurring pulmonary infection. The levels of MMP-9 and TNF-α were detected before treatment, after infection and 3 d after infection control. RESULTS The level of MMP-9 was (751.84±98.74) pg/ml after pulmonary infection in infection group, which was higher than (240.42±72.64) pg/ml of admission and (246.22±71.02) pg/ml of the same period in non-infection group. The level of TNF-α was (4.84±0.79) ng/ml after pulmonary infection in infection group, which was higher than (1.22±0.42) ng/ml of admission and (1.32±0.45) ng/ml of the same period in non-infection group (P<0.05). The level of MMP-9 reduced to (2.52±0.54) ng/ml in infection group after infection control 3d, which were higher than (1.30±0.51) ng/ml same period in non-infection group (P<0.05). The levels of MMP-9 and TNF-α were (784.51±71.61) pg/ml and (4.95±0.89) ng/ml after pulmonary infection in patients with plaque formation, which were higher than (714.46±61.27) pg/ml, (4.41±0.73) pg/ml in patients with intima-media thickness (P<0.05). CONCLUSION The levels of MMP-9 and TNF-α increased significantly after pulmonary infection in patients with carotid artery atherosclerotic cerebral infarction, but reduced after infection control, so it will help to early identification and prognosis evaluation of clinical pulmonary infectio.