Abstract: OBJECTIV To study the expression of Chlamydia pneumoniae antibodies IgG and IgM in patients with unstable angina and analyze the related factors for infection. METHODS Totally 40 patients with untable angina who were treated in the hospital from Aug 2014 to Aug 2015 were chosen as the observation group, meanwhile, 40 healthy people who received physical examination were set as the control group. The expression of TNF-α, CRP, tPA, and PAI-1, as well as CpnIgG and CpnIgM in the two groups of participants were detected, the related data was observed and compared between the two groups, the result of detection of TNF-α, CRP, tPA, PAI-1, and Cpn antibodies was observed, and the levels of C.pneumoniae antibody IgG and the monitoring indexes were compared. RESULTS There was no significant difference in the tPA level between the two groups. The levels of TNF-α, CRP, and PAI-1 of the observation group were respectively (2.84±0.26)μg/L, (6.82±1.10)mg/L, and (0.82±0.12)AU/ml, higher than (0.60±0.28)μg/L, (2.47±0.70)mg/L, and (0.45±0.14)AU/ml of the control group, and there was significant difference (P<0.05). There was no significant difference in the positive rate of Cpn-IgM between the two groups; there was significant difference in the positive rate of Cpn-IgG (P<0.05). There was no significant difference in the HDL-C level between the two groups. The levels of TC, TG, LDL-C, PAI-1, CRP, and TNF-α of the positive group were respectively (4.92±0.89, 1.87±0.59, 2.56±0.68)mmol/L, (0.79±0.24)AU/ml, (5.26±1.30)mg/L, and (2.19±0.68)μg/L, higher than (4.22±0.75, 1.18±0.31, 2.19±0.56)mmol/L, (0.38±0.11)AU/ml, (2.70±0.86)mg/L, and (1.06±0.34)μg/L of the negative group. The tPA activity of the positive group was (0.43±0.05)IU/ml, less than (0.52±0.07)IU/ml of the negative group, and there was significant difference (P<0.05). CONCLUSION The C.pneumoniae antibody IgG is closely associated with the unstable angina, it may promote the release of inflammatory factors, induce the emergence of CRP and TNF-α, and interfere with plasmid lipid metabolism so as to lead to the unstable angina.