In the late Ming Dynasty, Xu Guangqi and other Catholic literati were actively involved with military affairs because of the invasion of Manchu and the threat of roving bandits. They imported cannons and gunners from Macau, and also worked hard to introduce European fortification, i.e., the trace Italienne. This paper has six parts. The first and second one illustrates how Xu and his student Sun Yuanhua, made their sustained efforts in building bastions. Then, based on the translation “Western Fortress” by Han Yun and Han Lin brothers (also Xu’s students), the Italian source and the transition of certain technology are explored. Part 4 focuses on Ma Weicheng, who allegedly directed the building of 32 bastions between the year of 1638 and 1643. Part 5 surveys the spread of the knowledge of trace Italienne in Qing dynasty. The final part discusses the reasons why the art of European fortification ended prematurely in early modern China.