Objective:　To explore the therapeutic effect and safety of thrombolysis and pure anticoagulation therapy in patients with acute submassive pulmonary embolism. Methods: A total of 63 patients with acute submassive pulmonary embolism were randomly divided into thrombolysis group (n=32) and pure anticoagulation group (n=31). Arterial blood gas index and right heart functional index changes of two groups were observed before treatment and after two-week treatment, and their therapeutic effects were compared and analyzed. Incidence of bleeding and thrombocytopenia were counted in two groups. Results: Compared with before treatment, there were significant improvements in arterial blood gas and right heart functional indexes after treatment in two groups, P<0.05 or <0.01; compared with pure anticoagulation group, there were significant rise in partial pressure of oxygen in artery [PaO2,（77.8±7.3）mmHg vs. (83.4±8.7) mmHg], right ventricular anterior wall motion [RVAWM, (4.9±1.7) mm vs. (5.8±2.2) mm]; and significant descent in alveolar-arterial oxygen difference [P (A-a)O2, (23.1±2.8) mmHg vs. (16.5±2.4) mmHg mmHg], pulmonary artery systolic pressure [PASP, (54.6±7.9) mmHg vs. (34.2±7.5) mmHg] in thrombolysis group, P<0.05 or <0.01. Total effective rate of thrombolysis group (100%) was significantly higher than that of pure anticoagulation group (80.6%), P=0.002. There were no significant difference in incidence rates of bleeding and thrombocytopenia between two groups, P>0.05. Conclusion:　Thrombolysis therapy can significantly lower pulmonary artery pressure and improve oxygenation and right ventricular function indexes in patients with acute submassive pulmonary embolism. It may be a preferred recommendation for patients without contraindications.