Objective To explore the value of high frequency ultrasound in analyzing the etiology of dysfunction after tendon repair. Method Fifty two patients who had finger dysfunction after tendon repair were included. The injured places were scanned with high frequency ultrasound in order to analyse the etiology of dysfunction, and treated according to ultrasound reports. Results According to ultrasonoscopy, the types of connection after tendon repair were divided into tendon connection, scar connection and non connection: ① Nine tendons were tendon connection, one with bone fracture. ② Sixty five tendons were scar connection, sixty three complicated by adhesion, one was stopped by bone-fiber tunnel and one complicated by tendon lax. ③ Nine tendons were non connection. Finger movement improved after undergoing rehabilitation or surgery according to the ultrasound reports. Conclusion The etiology of finger dysfunction after tendon repair could be distinguished by high frequency ultrasound, which would be helpful in guiding further treatment.