Abstract: OBJECTIVE To analyze the changes of serum d-d, CRP and Fib（d-dimer/d-dimer, c-reactive protein/c-reactive protein and fibrinogen/fibrinogen） in hospitalized patients with acute st-segment elevation myocardial infarction complicated by pulmonary infection. METHODS A total of 98 cases of patients with acute st-elevation myocardial infarction complicated with lung infection admitted to the north of hebei college affiliated first hospital from Jan. 2016 to Dec. 2017 were selected as study team, and 98 healthy people who underwent the physical examination at the hospital during the same period were selected as control group. The blood D-D, Fib and CRP of two groups of study objects were compared and analyzed, and blood D-D, Fib and CRP levels of patients with different infection types, different age and different dangerous degree of risk in study group were compared. RESULTS There were 35 cases of bacterial infection, 32 cases of fungal infection and 31 cases of fungal bacterial mixed infection in the study group. The blood D-D, FIB and CRP of the study group were（563.03±19.11） mg/L,（5.42±0.64） g/L and（84.40±6.90） mg/L, respectively, significantly higher than those of the control group（P＜0.001）. There were no significant difference of D-D among patiens with mixed infection, bacterial infection and fungal infection. The FIB and CRP of patients with bacterial infection and mixed infection were（5.39±0.40）g/L,（6.38±0.50） mg/L and（84.33±7.09）g/L, and（97.44±8.44） mg/L, respectively, significantly higher than those of patients with fungal infection, while those parameters in patients with mixed infection were all significantly higher than those in patients with bacterial infection group（P＜0.05）. Blood D-D, FIB and CRP of 65-82-year-old patients were（634.06±18.94） mg/L,（6.03±0.34） g/L, and（8.45±6.89）mg/L, respectively, significantly higher than those of 50-65-year-old patients（P＜0.001）. There were significant difference of D-D, FIB and CRP among patients in high, middle and low-risk patients（P＜0.05）, with high-risk patients being high and low-risk patients being low. CONCLUSION The blood D-D, Fib and CRP levels of patients with acute st-segment elevation myocardial infarction complicated with pulmonary infection will be increased, and the changes in blood d-d, Fib and CRP levels can help reflect the condition.