Goal Due to the development of medical technology, implementation of national health insurance (NHI) program and population aging, the increasing of ventilator-dependent patients are significant within these years. Patients with the catastrophic illness certification spent about 26.2% NHI medical resource. Oncology, hemodialysis and ventilator-dependent patients were thought to be the most resource utilized ones. The objective of this study was to find the possible risk of reintubation on those ventilator-dependent patients. So, that we may reduce the reintubation rate and shorten their hospital stays. Method This study was a retrospective study based on the database of a local teaching hospital. During 2005 and 2010, patients aged older than 17 years old and required more than 3 weeks of mechanical ventilation support were selected. Here were total 313 cases include 247 successful weaning and 66 reintubation. Statistical analysis included descriptive statistic, Chi-square test and logistic regression by SPSS® for windows. Risk factors included their demographic features, acute physiology and chronic health evaluation (APACHE) II scoring system as well as laboratory data. Results The ages of successful weaning and reintubation patients were 72¡Ó15 vs. 76¡Ó15, p=0.092 years old, respectively. APACH II score (17¡Ó8 vs. 22¡Ó8, p<0.001), BUN (33.2¡Ó26 vs. 43.0¡Ó33 mg/dL, p=0.033), K+ (3.8¡Ó0.8 vs. 4.2¡Ó0.9 mmol/L, p=0.002), Ca+ (8.0¡Ó0.8 vs. 8.6¡Ó0.9 mmol/L, p=0.007), WBC (13880¡Ó7270 vs. 17720¡Ó9540, p=0.003), Hb (11.8¡Ó2.5 g/dL vs. 10.3¡Ó1.4 g/dL, p<0.001), Platelet (224400¡Ó106310 vs. 284570¡Ó119160,p=0.001). However, Logistic regression found two significant factors were APACHE II (odds ratio [OR], 2.97), Hb (OR, 0.701). By means of ROC curves, we derived the critical values of reintubation risk due to Hb as 11.3 g/dL respectively. Conclusion Based on the results, we inference that the reintubation risk increases up to 1.2 per unit APACHE II score while decreases 45% per unit Hb. It is suggested that if clinical physician could keep Hb of patients above 11.3 g/dL respectively, the reintubation rate may be significantly reduced.