Objective To identify the surface electromyographic (sEMG) characteristics of bilateral stemocleidomastoid muscles in infants with congenital muscular torticollis (CMT) after rehabilitation.Methods One hundred and twenty two infants were enrolled from Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine between January 2013 and December 2015,including 63 cases receiving rehabilitation (treatment group) and 59 cases without rehabilitation (control group).The sEMG parameters of bilateral sternocleidomastoid muscles in cervical neutral,left and right rotation and stretching posture in the supine position were retrospectively collected before and after treatment/follow-up;and the root mean square (RMS) was analyzed.Results Before treatment,the RMS values of the affected side in cervical neutral position,cervical rotation and stretching posture were significantly lower than those of the unaffected side in both groups(t=15.758 and 11.950,4.871 and 4.746,4.142 and 4.318,P＜0.01).In the follow-up for control group,the RMS values of the affected side in cervical neutral position,cervical rotation and stretching posture were significantly lower than those of the unaffected side (t=10.692,2.198 and 3.239;P＜0.01,=0.03 and ＜0.01).In the treatment group there were no significant differences in the RMS values in cervical neutral position,cervical rotation and stretching posture between affected side and unaffected side after treatment(t=1.647,1.090 and 0.136,P=0.10,0.28 and 0.89).Conclusion Rehabilitation reduces the difference of the RMS values between the affected and unaffected sternocleidomastoid muscles in infants with CMT.