Spinal motor control can provide substantial insight for the causes of spinal musculoskeletal disorders. Its dynamic characteristics however, have not been fully investigated. The objective of this study is to explore the dynamic characteristics of spinal motor control via the fractional Brownian motion mathematical technique. Spinal curvatures and repositioning errors of different spinal regions in 64 children age 11- or 15-years old during upright stance were measured and compared for the effects of age and gender. With the application of the fractional Brownian motion analytical technique to the changes of spinal curvatures, distinct persistent movement behaviors could be determined, which could be interpreted physiologically as open-loop behaviors. Moreover, it was found that the spinal motor control of 15-year-old children was better than that of 11-year-old children with smaller repositioning error and less curvature variability as well as shorter response time and smaller curvature deformation.