Kulangsu Island, a Historic International Settlement, is a World Heritage site in China. Its typical heritage feature is the multi-cultural attributes. The modern western-style buildings on Kulangsu Island are influenced by the local culture of Fujian Province, China and foreign cultures from the Southeast Asia and western world. This paper uses Shape Grammar, a research method to analyze the feature of graph generation and combination by graphical method, as a facade analysis tool to excavate the prototype of the facade composition and summarize its rules. What’s more, a digital facades generation method of these architectural heritages is designed with Grasshopper software and stable diffusion, an AIGC image generation tool. Through the above steps, this paper aimed to create an approach of automatically generating architecture facades with Kulangsu style. This method can be helpful to analyze the cultural value and artistic value of architectural heritage, so as to help the protection strategy, renovation direction and cultural demonstration of architectural heritage.