Purpose The purpose of this study was to evaluate the value of diagnosing delaminated tears and ultrasonic characteristics on real‐time dynamic ultrasound. Materials and Methods We enrolled 143 consecutive patients who underwent arthroscopic rotator cuff repair between April 2020 and January 2021. All patients were examined using real‐time dynamic ultrasound of the shoulder within 2 weeks before arthroscopy. In our study, delaminated tears were defined as intratendinous horizontal splitting with or without the retraction of the articular or bursal layer of tendon. Delaminated tears were classified into three types on the basis of their shape: greater retraction of the articular layer (type I), greater retraction of the bursal layer (type II), and equal retraction of both layers (type III). The sensitivity and specificity of real‐time dynamic ultrasound for evaluation of delaminated tears were calculated using arthroscopy findings as the gold standard. Ultrasonic imaging appearances of delaminated rotator cuff tears were further described. Results Of the 143 patients, 47 (32.9%) had delaminated tears as confirmed by arthroscopy; 35 of these tears involved the supraspinatus tendon and 12 involved both supraspinatus and infraspinatus tendons. Real‐time dynamic ultrasound correctly diagnosed 36 of 47 delaminated tears with sensitivity 72.0% (57.2%–83.3%) and specificity 96.7% (90.2%–99.2%). Moreover, type I tear (n = 32) was more common than type II (n = 11) and type III tears (n = 4). Real‐time dynamic ultrasound evaluated shape of type I, type II, and type III with a sensitivity and specificity of 56% and 80%, 72% and 83%, and 100% and 98%, respectively. Anechoic horizontal linear splitting of tendon, unequal retraction of the bursal and articular layers, and thinning of the suffering tendon were the three signs observed during real‐time dynamic ultrasound examination. These three signs were indicative of a diagnosis of delaminated rotator cuff tears with high specificities (100.0%, 100.0%, and 97.9%, respectively) but relatively low sensitivities (25.5%, 25.5%, and 36.2%, respectively). Conclusion Real‐time dynamic ultrasound can be practically used for diagnosing delamination of rotator cuff tears with medium sensitivity and high specificity. Anechoic horizontal linear splitting of tendon, unequal retraction of the bursal and articular layers, and thinning of the involved tendon are the three important ultrasonic signs for diagnosis of delaminated rotator cuff tears.