Objective To investigate the ultrasonographic features of traumatic neuroma after mastectomy in breast cancer patients, so as to improve the cognition level of the disease. Methods The clinical and ultrasonic images of 9 patients with traumatic neuroma after mastectomy were analyzed retrospectively. According to the BI-RADS dictionary, the location, number, size, shape, boundary, internal echo, internal blood supply, the relationship with the peripheral nerve, and the elastic imaging score of some lesions were evaluated. Results There were 10 lesions in 9 cases of breast cancer, all in the muscle layer of the pectoralis major muscle near the scar, the size of the longitudinal diameter was 4.5 ～ 15.5 mm, the average (8.1 ± 2.2) mm, the diameter of the transverse diameter from 2.8 to 5.9mm, and the average (3.7 ± 1.1) mm. Of the 10 lesions, 7 were oval, 3 were round, 8 were with defined margins, and the other 2 were with poorly defined margins. The 10 lesions were heterogeneous hypoechoic, 8 lesions were parallel to the skin axis and 2 lesions were not parallel to the skin direction. In color Doppler examination, punctate color blood flow signals can be detected in 5 lesions. 7 lesions could be clearly shown to be connected to the peripheral nerves. The elastography score of 4 lesions was 1 lesion 2 points and 3 lesions 4 points. The final 6 lesions were evaluated as BI-RADS 4A and 4 lesions were evaluated as BI-RADS 4B. Conclusion The ultrasonographic features of the traumatic neuroma after mastectomy in breast cancer patients are low echo lesions, which are located in the layer of the pectoralis major muscle, elipse, clear boundary, and parallel to the skin,which can be clearly displayed in connection with nerve fibers, and shows a hard mass in elastic imaging.