Objective To investigate the expressions of platelet activation-dependent granule membrane protein and platelet-derived growth factor receptor-αB, and the ultra-microstructure changes of platelets in patients with acute ST-segment elevation myocardial infarction(STEMI). Method The expressions of platelet activationdependent granule of glycoprotein (CD62P)and platelet derived growth factor receptor αβ subtype (PDGFR-αβ)of platelets in peripheral blood in 36 patients with acute ST-segment elevation myocardial infarction(STEMI) hospitalized and another 34 healthy subjects over the same period (control group) were investigated by flow cytometry and data were analyzed. The changes of ultra microstructure and activity of blood platelets in those patients and control group were observed under the scanning electron microscope. Results The expressions of CD62P and PDGFR-αβin patients with STEMI group before treatment were (3.65 ± 1.87) % and (0.43 ± 0.39) %, respectively, and those after treatment were (0.96 ± 0.79) % and (0.28 ± 0. 24) %, respectively, whereas those in control group were (0.67 ± 0.35) % and (0.27 ± 0.22) %, respectively, which were much lower in control than those in patients with STEMI before treatment (P ＜ 0.01 or P ＜ 0.05) respectively. There were statistically significant differences in the expressions of CD62P and PDGFR-αβ in patients group between pre-treatment and posttreatment (P ＜0.01 or P ＜0.05), respectively. Obvious ultra-microstructure changes of platelet surface in patients with STEMI group were observed. Conclusions Due to platelet activation in AMI, the expressions of CD62P can be used as effective indicators for monitoring coronary heart disease, and the PDGFR-αβ can be used as a reference indicator. The platelet surface ultra-microstructure changes during platelet activation in patients with AMI can be found by scanning electron microscopy.