Objective To explore the impacts of different nutrition support methods on short-term outcome in critically ill adult patients. Methods We retrospectively reviewed the clinical data of 1503 critically ill adult patients who needed nutrition support in an mixed intensive care unit (ICU) of a tertiary care university hospital from January 1994 to December 2009. The complication of nutrition support, length of stay (LOS) in ICU, morbidity of infection and multiple organ dysfunction syndrome (MODS), and mortality among different nutrition support methods were compared. Results The Nutritional Risk Screening (NRS) scores of the enrolled patients were no less than 3. LOS in early enteral nutrition (EN) patients were significantly shorter than those in not-early EN patients (P ＜ 0. 001) and parenteral nutrition (PN) patients (both P ＜ 0. 001). Infection rate (P ＜ 0. 001),morbidity of MODS (P ＜ 0. 001) and mortality (P ＜ 0. 001) were significantly lower than those in not-early EN and PN patients. LOS of patients receiving PN rich in glutamine (Gln) was significantly shorter than that in conventional formula (P = 0. 0000). Morbidity of infection (P= 0. 0252) and MODS (P = 0. 0030), mortality (P =0. 0305) were significantly lower than that of conventional patients. LOS of patients receiving intensive insulin therapy (IIT) was significantly shorter than that of controlled group (P = 0. 0000). Morbidity of infection (P =0. 0001) and MODS (P = 0. 0237) and mortality (P =0. 0427) were significandy lower than those of controlled group. Conclusions Nutritional risk is prevalent among critically ill adult patients. Early EN, PN of rich in Gln,and receiving IIT can shorten LOS, decrease morbidity of infection and MODS, and improve prognosis among these patients.