Objective Traditional scoliosis orthosis has some disadvantages, such as long manufacturing cycle, high material consumption and unclear biomechanical effect. In order to solve these problems, this study intends to use finite element analysis to optimize the design of 3D printing scoliosis orthosis with computer-aided design, so as to achieve good mechanical strength and lightweight model. Method A hand-held three-dimensional scanner was used to scan the body contour of volunteers, and then the body surface model was imported into the three-dimensional modeling software for modeling processing. The CT data and X-ray film of volunteers were analyzed. According to the three-point force principle, traction and load-free principle, the body surface model was modified, and the pressure area and release area were designed. The model of scoliosis orthosis was designed preliminarily. Then, the local optimization of 32 different sizes of hollow combination is studied. According to the optimization results, the model of scoliosis orthosis was hollowed out and analysed biomechanically. The stress distribution of the 3D printing scoliosis orthosis designed by hollowing out was compared to verify the optimization effect of the orthosis model. Results For the current 3D printing scoliosis orthosis, a 3D printing scoliosis orthosis with lighter weight, better air permeability and sufficient strength can be obtained by suing optimal design of local hollowing out with 9mm radius and 23mm spacing round holes (local weight loss of about 40%). Conclusion Based on the finite element biomechanical analysis, with hollowing out optimization design, 3D printing scoliosis orthosis can achieve the advantages of less printing materials and increased air permeability, and ultimately improve the wearing comfort and compliance of patients.