Objective To investigate the application value of ultrasonography in evaluating the peripheral neuropathy of neurofibromatosis type I (NF1). Methods The ultrasonic manifestations of peripheral neuropathy in 11 cases of NF1 confirmed by clinic or pathology were retrospectively analyzed. The amount, position, range, internal echo, vascular distribution, and the relationship with peripheral nerve and tissue of peripheral nerve lesions in NF1 were observed. Results The ultrasonic characteristics of peripheral neuropathy in NF1 showed as neurofibromas of varied sizes, multi focal distribution, and multiform performances. They were divided into three types. 5 cases were multiple nodular types. They appeared as round, lobulated and spindly, clear boundary and solid hypoechoic mostly. 4 cases were of plexiform type. The involved neural trunks were deformed, distorted, and thickened. The lesions were plexiform hypoechoic and grew axially along the neural trunks. 2 cases were of diffuse type, manifested as subcutaneous fat layer thickening with fuzzy borders, flaked hyperechoic with linear, cord like hypoechoic distribution. 3 cases of recurrence in this group were malignant Schwannoma. The sizes of tumor were larger. The internal echoes were heterogeneous. The internal vessels were abundant. The surrounding tissues were infiltrated. Conclusions Ultrasonography can clearly display the features of involved peripheral neuropathy in NF1; provides objective and exact evidences to clinical diagnosis. At the same time ultrasonic follow-up also plays an important role in finding recurrence and malignant transformation of peripheral neuropathy in NF1.