Abstract: To study the mechanical properties of plate-rod system for scoliosis (PRSS), a model of scoliosis and correcting clamp was built on the base of similar principle. According to the factual situation, the distribution of model centrum stress was measured by using photoelastic method and the stain of the spine was tested by strain gauges method simultaneously. The results indicated that compressive stress was formed on the convex side of scoliosis model by the effect of portrait loading. On the other hand, when PRSS was applied, compressive stress of the concave side of model centrum came to little and became tensile stress with transverse correcting loading.