Objective To investigate the EMG characteristics and clinical application value of surface EMG in cervical muscle group of children with congenital muscular torticollis (CMT). Methods A retrospective analysis was performed on 478 children diagnosed as CMT from January 2018 to August 2022 in Rehabilitation Center of the Children's Hospital Affiliated to Chongqing Medical University. The torticollis side of the same case was included in observation group and the healthy side was included in control group. Surface EMG was used to record the electromyography root-mean-square values of bilateral sternocleidomastoid muscles, platysma muscles and upper trapezius muscles in the rest and different exercise states. The difference of root-mean-square values between the affected side and the healthy side muscle groups at rest and under different exercise states and the diagnostic value were compared. Spearman correlation analysis was used to evaluate the relationship between the severity of congenital muscular torticollis on the affected side and the root mean square value of each cervical muscle group. Results The root-mean-square value of sternocleidomastoid muscle on the affected side of CMT children was higher than that on the healthy side during relaxation and lower than that on the healthy side during contraction, and the differences were statistically significant (P<0.05), the abnormal root-mean-square value of the affected side in the resting position and in all motion state has higher diagnostic value. The root-mean-square value of platysma muscle on the affected side was higher than that on the healthy side when it was in the resting position and the reverse neck rotation relaxed state (P<0.05), and lower than that on the healthy side when it was in the same neck rotation contraction state (P<0.05), abnormal values detected in resting sitting position and elevation of head have higher value. Root-mean-square value of upper trapezius muscle on the affected side was higher than that on the healthy side in the relaxed state (P<0.05). The abnormal values in sitting position, turning neck and bending head have high diagnostic value. The severity of CMT was positively correlated with the root-mean-square values of sternocleidomastoid muscle, platysma muscle, and upper trapezius muscle (r was 0.721, 0.612, 0.655, P<0.001). Conclusion sEMG could be used as a good method for the clinical diagnosis and evaluation of congenital muscular torticollis in children.