In China, the northeastern region has preserved many valuable modern built heritage buildings, which are undergoing difficult exploratory protection during the industrial and urbanisation process. Taking Dalian city as a case study, this article retraces the history of Dalian’s opening up and colonial management from the perspective of urban planning and historic district protection and management systems. This article sorts out the influence of national and local institutional policies on Dalian’s urban construction and development to analyse the past evolution, current problems and internal causes of the renovation and protection of Dalian’s typical historic districts. This influence is mainly reflected in the lack of protection and damage done to unofficial heritage, the disconnection between historic districts and the surrounding environments and urban textures, and the Chinese-style transformation and economic decline of exotic areas. This paper calls for attention to and the rapid clarification of the built heritage list, the improvement of planning and protection systems and related supporting policies, and a focus on the protection of the authenticity of colonial heritage. This paper provides strategic guidance for improving the protection of historic districts in Dalian in Northeast China and hopes to serve as a reference for the protection of built heritage in other nonfamous historic and cultural cities.