Objective Cerebral palsy(CP)is a progressive brain dysfunction syndrome.The bilateral spasm is the most common clinical symptoms.The selective posterior rhizotomy(SPR)is one of the commonly used operation for reducing spasm in cerebral palsy.This study was aimed to assess preoperative and postoperative gait characteristics in bilateral spastic cerebral palsy children after SPR. Methods Study included 12 cases children with cerebral palsy(6 male and 6 female),the average age was 6.2 years.During the same period,12 cases(6 male and 6 female)of age,sex, matched normal developed children were included in the control group, the average age was 6.1 years.Cadence,stance phase time percentage,swing phase time percentage, double limb support time percentage, stride length, velocity were documented in cerebral palsy children before SPR,6 months after SPR and control subjects. Results Compared with the preoperative group, GMFM score significantly increased after 6 months after surgery,it rose from(89.6±5.4)to(94.3±4.3), the difference between the two groups have statistical significance(P<0.05), MAS score decreased significantly after 6 months after surgery,it drop from(1.6±0.4)to(0.6±0.5), the difference between the two groups was statistically significant(P< 0.05).The stride length showed significant differences in preoperative and postoperative cerebral palsy patients and normal control children(P< 0.01).Compared with normal control children, preoperative cadence,stride length,stance phase time percentage,double limb support time percentage were significantly higher, meanwhile, swing phase time percentage, stride length, velocity were significantly lower in preoperative children(P<0.05).Compared with preoperative children, 6 months postoperative had decreased cadence,stance phase time percentage and increased stride length, swing phase time percentage(P<0.05).Double limb support time percentage and velocity showed no significant difference preoperatively and postoperatively. Conclusion The SPR can significantly improve the functional gait performance in cerebral palsy children, the gait analysis can be used as postoperative evaluation factors after the SPR. Key words: Cerebral palsy; Bilateral spastic type; Selective posterior rhizotomy; Gait