Objective To compare the efficacy of reteplase and ateplase in the treatment of acute massive pulmonary thromboembolism ( PTE) in emergency. Methods From January 2005 to December 2009,42 patients with acute massive PTE were treated by intravenous thrombolysis with reteplase or ateplase. The thrombolysis efficacy, bleeding incidence and mortality were measured. Results In the reteplase group, the emergency thrombolysis effective rate was 88. 9% among 18 patients. Mild bleeding occurred in 3 patients,moderate bleeding in 1 patient, and 2 cases died in hospital. In the ateplase group, the emergency thrombolysis effective rate was 75% among 24 patients. Mild bleeding occurred in 3 patients, moderate bleeding in 2 patients, and 3 cases died in hospital. The thrombolysis effective rate, bleeding incidence and mortality had no significant difference between the two groups. Conclusion Both the reteplase and ateplase thrombolysis therapy are safe and effective in the treatment of acute massive PTE, but reteplase thrombolysis therapy is more convenient in emergency.