Aim To study the relationship between the occurrence of acute coronary syndrome (ACS) and hypercoagulable state. Methods Plasma prothrombin fragment 1 and 2 (F_ 1+2) and soluble fibrin monomer complex (SFMC) were detected by enzyme-linked immunosorbent assay for 86 patients with ACS and 75 patients with stable angina pectoris (SAP). Results Compared with SAP group, the plasma levels of F_ 1+2 and SFMC in ACS group were significantly higher (F_ 1+2: 1.21± 0.23 nmol/L vs 0.76±0.20 nmol/L, p<0.001; SFMC: 85.4±12.4 mg/L vs 68.7±13.8 mg/L,p<0.001). The plasma levels of F_ 1+2 and SFMC in ACS patients with diabetes mellitus were significantly higher than those in ACS patients who had no other diseases (F_ 1+2: 1.28±0.19 nmol/L vs 1.16±0.20 nmol/L, p<0.05; SFMC: 89.8±12.4 mg/L vs 82.7±13.7 mg/L,p<0.05). The plasma levels of F_ 1+2 and SFMC in ACS patients with essential hypertension were significantly higher than those in ACS patients who had no other diseases (F_ 1+2: 1.26±0.24 nmol/L vs 1.16±0.20 nmol/L, p<0.05; SFMC: 90.0±12.8 mg/L vs 82.7±13.7 mg/L, p<0.05). Conclusion Patients with SAP were in stable thrombotic state, patients with ACS were in unstable thrombotic state, the occurrence of ACS was closely related to hypercoagulable state.