To　study　the　stress-strain　relationships　of　intervertebral　discs　and　vertebrae　when　using　a　plate-rod　system　for　scoliosis,　a　mechanical　model　of　scoliosis　was　built　based　on　the　similarity　principle.　The　stress　variation　on　the　spine,　which　was　under　the　coactions　of　lengthwise　load　and　correcting　load,　was　measured　by　photoelastic　and　strain　gauge　methods.　The　model　test　results　indicate　that　the　added　value　of　compressive　stress　on　the　concave　side　of　the　spine　(0-1.5　MPa)　is　larger　than　the　added　values　of　compressive　stresses　on　the　spine＇s　convex　side　and　concave　ligament　(0-200　N).　This　demonstrates　that　the　lengthwise　load　(weight)　can　increase　the　seriousness　of　scoliosis.　In　addition,　it　was　shown　that　tensile　stress　is　formed　on　the　concave　side　of　the　scoliosis　model　when　the　compressive　stress　decreases　(1.5-0MPa),　due　to　the　effect　of　the　correcting　load.　It　can　be　seen　that　plate-rod　systems　can　correct　scoliosis　effectively.　©　2010　Informa　UK,　Ltd.