Objective The aim of this study was to investigate the application of low molecular weight heparin combined with alteplase for thrombolysis in patients with acute myocardial infarction(AMI),and to compare its thrombolysis effect with traditional anticoagulant-general heparin. Methods 35 AMI patients with alteplase intravenous thrombolytic therapy were divided into two groups,among which 15 cases in the study group were treated with 30 mg enoxaparin instant intravenous injection before thrombolysis,40 mg enoxaparin hypodermic injection 15 minutes after thrombolysis,40 mg enoxaparin hypodermic injection every 12 hours for 5 days. The other 20 cases were assigned to the control group and treated with 4 000 u(or 60 u/kg)general heparin instant intravenous injection,then pumped general heparin intravenously in the rate of 800-1 000 u/h. Meanwhile,detected coagulation convention every 3 hours and adjusted the dose of heparin according to the activated partial thromboplastin time(APTT)to keep APTT value within 1.5 to 2.0 times(50-70 s)the standard value. 48 hours later,patients in the control group was given hypodermic injection of 40 mg enoxaparin every 12 hours for 5 days. All cases were given regular treatment as guidelines recommended. Results The patency rate of infarct-related coronary artery assessed by unified clinical criteria was 86.66% and 65.00%,and the average recanalization time was(1.62±0.36)h and(1.81±0.33)h in the study and control groups,respectively. There were no significant differences on patency rate and recanalization time between the two groups(P > 0.05). One case of bleeding complication occurred in the study group(6.66%),while five cases occurred in the control group(25.00%). In the two groups,no cases appeared intracranial hemorrhage and other serious or fatal bleeding occurred. Conclusion The clinical efficacy of low molecular weight heparin was non-inferior to general heparin in AMI patients with alteplas thrombolysis. The application of low molecular weight heparin was simple and easy to operate. It can optimize the procedure of thrombolysis,reduce repetitive coagulation index monitoring and lessen clinical workload,which is worth being promoted to primary hospital and the emergency systems.