北京旧城始于元朝，繁荣于明清，民国以来基本保持原貌。“北京旧城是都市计划的无比杰作”，“是历代都城发展的最辉煌的结晶”。解放后，由于首都行政中心职能的增加及城市本身的快速发展，北京旧城发生了巨变。城市在获得现代化的同时，传统特色也在不断消亡，能否寻找到一条北京旧城保护与发展的双赢之路成为本论文研究的目的所在。论文回顾了北京旧城半个世纪以来的更新改造，特别是研究、分析了1990—1997年、1998—2004年两次大规模改造的背景、动因及结果，试图找出其发展规律。为进一步说明问题，还例举了东城区近年来危旧房改造的实例。笔者对北京市第一批危旧房改造项目——菊儿胡同做了深入、细致的调查工作，分别走访了菊儿胡同的开发单位、设计人、居民和居委会，证实菊儿胡同危改确实是北京旧城有机更新的成功范例。同时分析了菊儿胡同危改三期、四期未能启动的原因，并对其未来进行了展望。在批判旧城大规模改造带来的负面影响之后，笔者介绍了曾经主持的旧城小规模危房改造的试验，并得出一些有意义的启示。文中还介绍了皇城根遗址公园环境整治工程，这个实例证明了政府在旧城更新过程中可以发挥巨大的作用。论文最后提出，北京旧城整体保护的出路在于：“观念更新”，“机制创新”，推进住房私有化进程，鼓励产权人“自我更新”，最终实现北京旧城的“有机更新”。

The old city of Beijing was built from Yuan Dynasty and prospered in Ming and Qing Dynasty. The main structure of the old city remained almost the same from the latter-day. It was admired as an incomparably excellent urban planning work, or a glorious result of the development of ancient capital cities. After the liberation, the old city encountered great changes because of the insert of other functions, which might be regarded as the progress of modernization, but also destroyed the traditional features in the inner city. So the efforts to a win-win road between conservation and development of the old city should be made, which is also the aim of this thesis.This thesis reviews the urban renew process during the past 50 years, especially the two great-scale reconstruction, its background, its reasons and its result, trying to reveal the disciplinarian under the surface of the phenomena. To extend the discussion, several examples in the eastern area of Beijing are given and analyzed.The author investigated Juer Hutong, one typical project, which was the first passel of reconstructing the dangerous houses. Those once involved in this project, the developers, the designers, the households, and the committees, were interviewed. They mostly stressed that the project of Juer Hutong was a success model in urban renewal in Beijing. Also the reason why the third and fourth phases of Juer Hutong were not implemented was analyzed.The conclusion is that the great-scaled reconstruction have many negative effects, and we introduced several examples of small-scaled reconstruction, gave some advices about the reconstructions of the old city, including the role of the government during the progress.As a consequence, the best way of the renewal in Beijing may be: rethinking, renovation, giving private-property, encouraging self-renewal, and finally “organic redevelopment”.