As the defense core of the Northeast region, the construction of the city defense system of Jilin Garrison city has played an important role in resisting foreign enemies and maintaining local stability. Jilin Garrison city has assumed the important functions of stabilizing the border and defending Shengjing. This also makes it occupy a core position in the defense system of Northeast China in the Qing Dynasty. Therefore, this study intends to analyze the spatial structure and defense system of Jilin garrison city from 1867 to 1907 with the existing relevant data of the Qing Dynasty as the center. Jilin Garrison City was originally established as a military castle with a single function, and a simple and effective defense structure was built with its geographical advantages. The Eight Banners system is the basis of the city's defense system. With different historical periods, the defense facilities have undergone many adjustments and gradually adapted to the military needs of the era of hot weapons. The core defense area in the city is the General's Office, and the military facilities that provide gunpowder and weapons are mainly distributed outside the city. The cooperation inside and outside the city has formed a multi-level, three-dimensional defense network. The garrison cities in the jurisdiction are connected to Jilin Garrison city through post roads, building a linkage defense system with Jilin Garrison city as the command center.