Objective To compare the clinical features and high frequency colour Doppler ultrasound’s diagnostic value in testicular torsion between neonates and infants under 1 year old.Methods We collected 40 cases of testicular torsion aged less than 1 year old from 20042015, and analyzed the clinical characteristics and the imaging features of high-frequency colour Doppler ultrasound, respectively.Results 21 neonates were collected. The mass of scrotum or inguinal area were found in 19 cases. 16 cases were solid mass (10 neonates were found solid, nontender scrotal mass when were born ). 3 cases were soft mass. 4 neonates showed restlessness. 5 cases were extrathecal torsion. No cryptorchidism with torsion were observed in this group (P=0.002). For infants group, 19 cases were collected. 11 soft mass of scrotum or inguinal area were found. 8 infants showed restlessness. The scrotal redness or swelling in the affected side or inguinal area were observed in 7 cases. The cryptorchidism with torsion in 7 cases, and intravaginal torsion in 8 cases (P=0.003). The main presentations of the ultrasonic images in neonates and infants were testicular swelling or shrinking. The parenchymal echo was homogeneous or not. The peripheral anechoic areas in some testicles, and the presentations of colour Doppler flow imaging (CDFI) showed that there was no or a few blood flow signals. The circular “string of beadslike” or “eggshelllike” hyperechoic areas was the characteristic of neonatal testicular torsion only can be seen in neonates. All neonates and infants undertook a surgery. The orchiectomy was performed in neonates and infants (P=0.056). In the follow up of neonates and infants by ultrasound after operation, the testicular torsion were healed in 4.7% of the neonates and 368% of the infants (P=0.017). Conciusion Intravaginal torsion were more often seen in infants, and extravaginal torsion were more often seen in neonates. The morbidity of undescendent testes in infants was 368%. The ultrasound has a high sensitivity and specificity in diagnosis of testicular torsion in neonates and infants, and there were some significant different characteristics in the two groups. Orchiectomies was performed less in the infant group.