Abstract: Objective To investigate dynamic changes of D-dimmer in thrombolytic therapy of acute myocardial infarction cases. Methods 50 cases of acute myocardial infarction （AMI）patients were involved into this study. The AMI patients according to whether patients carried out thrombolytic therapy were divided into reperfusion group and non thrombolysis group. According to the ST segment elevation, the patients were divided into ST-segment elevation myocardial infarction (STEMI）group and non ST segment elevation myocardial infarction group (NSTEM）group. The D-dimmer levels in 50 cases patients before and after 6, 12 and 24 hours treatment, and 30 cases of healthy people were measured. Results The D-dimmer level in the basic state of AMI group was higher than the control group, but without statistically significant (P> 0.05). Before treatment, the D-dimmer level was no significant difference in the thrombolysis group and non thrombolysis group (P> 0.05). After 6h, 12h, 24h treatment, the D-dimmer levels in thrombolysis group and non thrombolysis group compared with those before treatment were significantly different (P<0.05). Before treatment, the D-dimmer level in the STEMI group was higher than the NSTEM group, but without statistically significant (P>0.05). After 6h, 12h, 24h treatment, the D-dimmer levels in STEMI group and NSTEMI group compared with those before treatment were significantly different (P<0.05). Conclusion The D-dimmer detection could display the dynamic evolution of AMI thrombolytic therapy. It could have significance in the diagnosis, treatment and prognosis on acute myocardial infarction.