Abstract: OBJECTIV To observe the changes of serum RAAS, MMP, TIMP indexes of heart failure patients complicated with pulmonary infections so as to provide guidance for prevention, diagnosis, and treatment of the pulmonary infections in the heart failure patients. METHODS Totally 46 heart failure patients complicated with pulmonary infections who were treated in hospitals from Jun 2014 to Mar 2016 were chosen as the group A, meanwhile, 46 patients with single heart failure were assigned as the group B, and 46 healthy people who received physical examination were set as the group C. The serum RAAS, MMP, TIMP indexes were compared among the three groups of study objects; the levels of serum RAAS, MMP, and TIMP were compared among the patients with different severities of pulmonary infection in the group A. RESULTS As compared with the serum RAAS indexes, the Ang-Ⅱ, ALD, and NE levels of the group A were respectively (65.75±5.24)ng/L,(39.45±3.36)ng/L, and (71.50±6.48)ug/L, higher than (58.45±4.63)ng/L,(32.52±2.73)ng/L, and(62.62±5.48)ug/L of the group B and (37.45±3.80)ng/L, (18.40±1.73)ng/L, and (33.23±3.13)ug/L of the group C. The serum MMP and TIMP levels of the group A were lower than those of the group B and the group C, which were lower in the group B than in the group C. There was significant difference in the serum RAAS, MMP, or TIMP level among the patients with different severities of pulmonary infections in the group A (P<0.05). CONCLUSION The heart failure patients complicated with pulmonary infections show high-expression state of serum RAAS, MMP, and TIMP indexes; it is necessary to attach great importance to monitoring and improvement of the above serum indexes of such group of patients.