OBJECTIVE To evaluate the correlation of pulmonary embolism (PE) and original diseases by retrospectively analysis of the patients for 20 years in single medical center. METHODS Five hundred and five patients with PE were admitted and treated in General Hospital of Chinese PLA from January 1989 to January 2009, and their clinical data were retrospectively reviewed to analyze the risk factors of PE and the correlations of PE with the original diseases. RESULTS Of the 505 patients with PE in the past 20 years, the incidence of PE was increased year by year, especially it increased spectacularly after the year of 2004 [61.2% (309) vs. 38.8% (196)]. It was found to be most prevalent in patients of 4160 years old. Its incidence in males was 1.52 folds higher than that of the females [60.4% (305) vs. 39.6% (200)]. Dyspnea, chest pain and hemoptysis were the initial symptoms in the PE patients. Among the 505 patients, 40.0% of them complained dyspnea with chest pain and hemoptysis. Among them, dyspnea occurred in 100.0% of patients, hemoptysis in 52.1%, and chest pain in 40.0%. In 31.1% of the patients if was complicated with deep venous thrombosis (DVT), 19.8% of them suffering from varicosity, 9.5% of them had the history of surgery less than 30 days before, 22.0% of them suffering from neoplasm, 3.6% of them were accompanied with cerebrovascular disease within 4 days, 17.4% of them were accompanied with infection, 10.1% of them were accompanied with primary pulmonary hypertension, and 16.8% of them were accompanied with heart diseases. Multivariate analysis showed that the history of surgery, DVT and neoplasm had significant correlation with the occurrence of PE [odds ratio (95% confidence interval), OR (95%CI) was 4.540 (2.186-9.443), 0.325 (0.155-0.682), 2.610 (1.020-6.708), P<0.05 or P<0.01], while oral contraception, primary pulmonary hypertension and cerebrovascular disease showed a less significant correlation with the occurrence of PE [OR (95%CI) was 0.297 (0.078-1.126), 3.210 (0.855-12.110), 2.939 (0.862-10.020), all P>0.05]. The age and infection did not show significant correlation with the occurrence of PE [OR (95%CI) was 1.041 (0.674-1.607) and 0.820 (0.410-1.665), both P>0.05]. CONCLUSION The PE is difficult in diagnosis, but with increasing cognizance, the diagnostic rate of PE has been increased. Patients with history of surgical operation, DVT or neoplasm, who complain dyspnea without known cause, chest pain or hemoptysis, should be subjected to further examinations, as to confirm the diagnosis of PE, then the survival rate of the patients with PE may be elevated.