Abstract: Objective To investigate the ultrasonographic features of ovarian torsion (OT) in infants. Methods Forty-nine infants with OT were selected as OT group, and 50 infants with ovarian mass but without OT were selected as control group. The ultrasonographic features of fluid-debris, grid, thick wall, supra-mural nodules, subcapsular effusion, enhanced ovarian echo with enlarged follicles, calcification, ascus and ovarian blood flow signals were observed and compared between the two groups. The diagnostic value of ultrasonography was evaluated by ROC curve. Results The sensitivity, specificity and accuracy of ultrasonography for diagnosing OT were 95.9%, 72.0% and 83.8% respectively. The area under the ROC curve was 0.840. The detection rates of fluid-debris, enhanced ovarian echo with enlarged follicles, calcification and subcapsular effusion in the OT group were significantly higher than those in the control group (P<0.05 or P＜0.01), while other signs showed no significant difference between the two groups (P>0.05). The ROC curve showed that the area under the curve of fluid-debris was 0.817, the sensitivity was 65.3% and the specificity was 98.0%. The area under the curve of enhanced ovarian echo with enlarged follicles was 0.684, the sensitivity was 36.7% and the specificity was 100.0%. The area under the curve of calcification was 0.613, the sensitivity was 34.7% and the specificity was 88.0%. The area under the curve of ovary subcapsular effusion was 0.551, the sensitivity was 10.2% and the specificity was 100.0%. Conclusion The ultrasonographic manifestations of OT in infants are diverse and variable. Ultrasonography has high sensitivity in the diagnosis of OT, and is the preferred method for the ultrasonographic assessment and differential diagnosis. Fluid-debris has the highest diagnostic value for OT and can provide reliable imaging basis for early diagnosis of OT.