To observe the impact of initial low-dose (trophic type) enteral nutrition (EN) support on mechanical ventilation (MV) time, the incidence of complications and survival rate in patients with acute respiratory failure (ARF). A prospective study was conducted. Forty-four patients with ARF undergoing MV admitted to Department of Critical Care Medicine of Hangzhou Traditional Chinese Medical Hospital from September 2015 to February 2017 were enrolled, and they were divided into a trophic feeding group (n = 23, study group) and a standard-dose feeding group (n = 21, control group). In the two groups, the EN support feeding was given to the patients through a nasogastric tube within 24-hour MV for consecutive 7 days, the protein supply to each one of all of them was 1.2-1.6 g×kg-1×d-1. The study group received EN according to non-protein calories of 41.84-83.68 kJ×kg-1×d-1 to calculate, while the control group accepted EN according to non-protein calories of 104.60-125.50 kJ×kg-1×d-1 to calculate. The serum albumin (Alb) and fasting blood glucose (FBG) levels were measured in two groups 1 day before EN treatment and at 1, 2, 3, 7 days of treatment, and the energy levels in initial 3 days and 7 days of MV and the 24-hour urine creatinine (UCr) level on the 7th day after treatment were recorded. The creatinine-height index (CHI, CHI = actual UCr/standard UCr) was calculated. The incidence of intestinal intolerance (vomiting, gastric retention, diarrhea, gastrointestinal bleeding, etc.) in 7 days of treatment, MV time, the length of stay in ICU, the total length of stay in the hospital and the 28-day incidence of new infections (pulmonary, hematogenous, urinary, abdominal, and other infections) and 60-day survival rate were observed between the two groups. The EN supplies within 3 days and 7 days in the study group were significantly lower than those in the control group [within 3 days (kJ/d): 1 710.58±703.96 vs. 4 152.79±1 334.65, 7 days (kJ/d): 2 471.28±815.50 vs. 5 058.08±875.25, both P < 0.05]; there were no statistically significant differences in CHI after EN therapy for 7 days and serum Alb levels before and after EN between the two groups. FBG level of the study group was significantly lower than that of the control group since the 2nd day of treatment (mmol/L: 8.58±2.37 vs. 10.93±3.75), and continued to the 7th day (mmol/L: 8.96±1.76 vs. 10.97±4.11, both P < 0.05), the incidence of elevated blood glucose was also significantly lower than that of the control group [26.1% (6/23) vs. 66.7% (14/21), P < 0.05]. The incidence of feeding intolerance in the study group was significantly lower than that in the control group from 2 days of treatment till 7 days (26.1% vs. 47.6%, P < 0.05). There were no statistically significant differences in MV time (days: 15.04±6.75 vs. 16.14±8.51), the length of stay in ICU (days: 16.52±6.89 vs. 17.24±7.67), total length of stay in hospital (days: 26.35±9.69 vs. 25.33±7.73), 28-day new infection rate [26.1% (6/23) vs. 42.9% (9/21)] and 60-day survival rate [65.2% (15/23) vs. 66.7% (14/21)] between the study and control groups (all P > 0.05). Initial trophic EN feeding results in clinical outcomes similar to those of early standard-dose EN feeding in MV patients with ARF, but the former one has less incidence of high blood sugar and more satisfactory gastrointestinal tolerance situation.