| To analyze the value of red cell distribution width (RDW) in the early mortality risk of pulmonary thromboembolism. Methods We collected 99 cases confirmed pulmonary thromboembolism from September 2011 to March 2014 in the First Affiliated Hospital of Dalian Medical University. The patients were divided into four groups according to the mortality risk: low-risk group, mediate-low-risk group, mediate-high-risk group and high-risk group. We analyzed the difference of RDW between the four groups and the correlation between RDW and brain natriuretic peptide (BNP), troponin I (cTnI) and D-dimer level. Results There were no significant difference in age, gender, hemoglobin, fibrinogen, low density lipoprotein, smoking history, tumor history, diabetes history, hypertension history and coronary heart disease among the four groups (P＞0.05). RDW was significantly different among the four groups (P<0.001). The average value of RDW increased with the rise of early mortality risk (r=0.558，P<0.001). RDW was positively correlated with BNP (r=0.44, P<0.001), cTnI (r=0.275,P=0.006), but not with D-dimer (r=0.002,P=0.981). Conclusion The increase of RDW (RDW>14.6%) would be used to evaluate the severity of PTE.