Objective：To retrospectively analyze the clinical characteristics，treatment and prognosis of intermediate-high risk acute pulmonary thromboembolism(APTE)patients，and to further provide basis for the selection of treatment strategies for intermediate-high risk APTE patients. Methods：A total of 55 hospitalized intermediate-high risk APTE patients who met the criteria from January 2016 to June 2019 in the First Affiliated Hospital of Nanjing Medical University were divided into the thrombolytic group(n=27)and the non- thrombolytic group(n=28)according to whether thrombolytic therapy was performed. The clinical data of the thrombolytic group and the non-thrombolytic group were compared，and the causes of thrombolytic therapy in the thrombolytic group were analyzed. Logistic regression was used to analyze the factors related to thrombolytic therapy in the intermediate-high risk APTE patients，and to compare the prognosis and incidence of adverse events in patients with different treatment regimens. Results：The proportion of first emergency visit，bilateral APTE and central APTE in the thrombolytic group was higher than that in the non-thrombolytic group，but the proportion of right ventricular enlargement/systolic dysfunction was lower than that in the non-thrombolytic group，the difference was statistically significant(P ＜ 0.05). Gender，lower extremity deep venous thrombosis，moderate to severe pulmonary hypertension，underlying diseases(including chronic pulmonary disease，hypertension，diabetes，coronary heart disease，cerebrovascular history，and malignant tumor)had no significant influence on whether thrombolytic therapy was performed. The percentage of D-dimer and peripheral blood neutrophil count in thrombolytic group was higher than that in non - thrombolytic group，peripheral oxygen saturation(SpO₂)was significantly decreased(P＜0.05)，arterial partial pressure of oxygen(PaO₂)had a downward trend.cardiac troponin T and N-terminal pro - B - type natriuretic peptidewere increased in the thrombolytic group，but the difference was not statistically significant. Logistic regression and receiver operating characteristic(ROC)curve analysis showed that SpO₂ was a factor related to thrombolytic therapy(P ＜ 0.05). The optimal cut-off value of SpO₂ was 91.5%. The nosocomial mortality of thrombolytic therapy and anticoagulant therapy was 0，but the incidence of bleeding of systemic thrombolytic therapy was higher than that of catheter - directed thrombolysis or anticoagulant therapy alone(P＜0.05). Conclusions：The reasons for thrombolytic therapy in intermediate - high risk APTE patients include low SpO₂，severe clinical symptoms，large emboli blocking pulmonary vessels，and heavy cardiac load. Low peripheral oxygen saturation is a factor associated with thrombolytic therapy. Compared with catheter - directed thrombolysis and anticoagulant therapy alone，systemic thrombolytic therapy has an increased risk of bleeding in intermediate -high risk APTE patients. Therefore，attention should be paid to the changes of the disease and appropriate treatment plan should be adopted，which may have positive significance for the diagnosis and treatment of intermediate-high risk APTE.