This study was established to evaluate the diagnostic value of ultrasonography in screening colorectal polyps in children and to discuss the necessity of colonic preparation before an ultrasonic examination.In this study, 288 children with colorectal polyps managed at our hospital between January 2007 and December 2016 were retrospectively reviewed. All patients were examined before and after basic colon preparation. The colorectal polyps were confirmed by colonoscopy/laparotomy and histopathology. Among all 288 patients, solitary polyps were identified in 278 patients (96.52%), and multiple polyps were identified in 10 patients (43 polyps) (3.48%) by colonoscopy/laparotomy and histopathology.By ultrasonic examination, 264 cases (264/278) were detected as solitary polyp and 9 cases (9/10) as multiple polyps (31 polyps). In 278 solitary polyps, 180 (64.74%) were detected by ultrasonic examination without a colon preparation. Following glycerine enema (10-20 mL) treatment, 264 (94.96%) cases were detected by ultrasonic examination. The sensitivity and specificity of ultrasonography with glycerine enema for the detection of colorectal polyps were 94.96% and 100%, respectively. Colon preparation significantly increased the proportion of polyps identified by ultrasonography (P < .0001), as well as the diagnostic rate of polyps in rectum, sigmoid colon and descending colon (P < .05).Ultrasonography can be the primary diagnostic method for screening colorectal polyps in children on the strength of its safety, validity, and accuracy. Basic colon preparation with glycerine enema is recommended for children, which enable the detection of intraluminal lesions before ultrasonic examination.