Objective To compare two asal-jejunal tube placement methods in critically ill patients with different acute gastrointestinal injury (AGI) grades, so as to discuss the value of AGI grading in selection of asal-jejunal tube placement. Methods A total of 156 patients with acute gastrointestinal injury in Intensive Care Unit (ICU) were observed prospectively; they included 30 cases of grade Ⅰ, 48 cases of grade Ⅱ, 50 cases of grade Ⅲ and 28 cases of grade Ⅳ according to the AGI grading system. And then the patients were randomly divided into treatment group and control group. The treatment group was given bedside ultrasound-guided nasal-jejunal tube placement, and the control group underwent bedside blind nasal jejunal tube placement. The success rate and average time of placement were observed in the two groups with different AGI grades, and then the correlation among AGI grading system, success rate and average time of placement were also analyzed in the two groups. Results The success rate of placement was high in AGI grade Ⅰ patients of the two groups, and there was no significant difference between the two groups(93.8% vs 92.9%). The success rates for AGI grade Ⅱ and grade Ⅲ patients of the treatment group were significantly higher than those of the control group(P<0.05). The successful placement rates were lower in AGI grade Ⅳ patients of the two groups and there was no significant difference between them. The average time of successful placement in AGI gradesⅠ,Ⅱ, and Ⅲ patients of the treatment group were significantly shorter than that of the control group (P<0.05); but there was no significant difference in AGI grade Ⅳ patients between the two groups. There was no significant correlation between AGI grade and successful placement rate. There was a positive correlation between AGI grade and the average placement time in the treatment group (P<0.05), but not in the control group. Conclusion Ultrasound-guided nasal-jejunal tube placement is obviously better than the blind method for AGI grade Ⅰ, Ⅱ, Ⅲ patients. The average time of ultrasound-guided nasal-jejunal tube placement is positively correlated with AGI grade, suggesting AGI grading system can help to choose naso-jejunal tube placement method.