Gastric reflux and aspiration are serious complications that threaten the life safety of patients during peri anesthesia. The prediction of gastric volume by bedside ultrasound in specific populations has been proven to be of definite value. In this review, the recent progress in the study of bedside ultrasound evaluation of gastric volume in special populations (including emergency patients, pregnant women, children and other patients not fully applicable to the current fasting guidelines) is summarized to improve the quality of anesthesia management in special populations and to promote its better application in clinical work.