一种提升车身后部扭转刚度的加强结构及其安装方法，属于汽车车身结构技术领域，该加强结构包括由后顶横梁上连接板、后顶横梁下连接板、C柱内板本体连接形成的空腔结构Ⅰ和由D柱下连接板、后围连接板、后尾灯安装板、侧围外板后连接板之间连接形成的空腔结构Ⅱ，空腔结构Ⅱ与空腔结构Ⅰ相连通并形成柱状空腔结构，空腔结构Ⅰ和空腔结构Ⅱ内设置D柱支撑组件，本发明的有益效果是，该加强结构保证了载荷传递的连续性，有效提升了白车身的扭转刚度，避免了车身行驶过程中局部产生大变形、共振和噪声问题，提高了关键接头处的刚度，避免了反复加载后局部薄弱点可能产生的疲劳破坏，同时也避免了在不良路况行驶过程中，产生的操稳和转向性能问题。

The invention relates to a reinforcing structure for improving the torsional stiffness of the rear of the vehicle body and an installation method thereof, belonging　to the technical field of vehicle body structure. The reinforcing structure comprises a cavity structure I formed by the connection of the upper connecting plate of　the rear top cross beam, the lower connecting plate of the rear top cross beam and the body of the C-pillar inner plate, and a cavity structure I formed by the　connection of the D-pillar lower connecting plate, the rear wall connecting plate, the rear tail lamp mounting plate The cavity structure II formed by the　connection between the rear connecting plates of the side wall outer plate, the cavity structure II is connected with the cavity structure I and forms a cylindrical　cavity structure, and the D-pillar support assembly is arranged in the cavity structure I and cavity structure II. The beneficial effect of the invention is that the　reinforcing structure ensures the continuity of load transmission and effectively improves the torsional stiffness of the BIW, The problems of local large　deformation, resonance and noise during vehicle body driving are avoided, the stiffness of key joints is improved, the possible fatigue damage of local weak　points after repeated loading is avoided, and the problems of handling stability and steering performance during driving under adverse road conditions are avoided.