Ancient Chinese architecture from the Song dynasty is a prominent example of the ancient oriental architectures. The cai-fen system was a module system used for the carpentry of Song architectures, which was specified by the governmental manual, the Yingzao Fashi (State Building Standards) compiled by Li Jie [1103]. We present a rule-based approach for generation of ancient Chinese architectures from the Song dynasty. Based on the special module system and the hierarchical topology of structural patterns in traditional Chinese architectures, the approach parameterizes the wooden elements of buildings and formalizes the construction rules for different architecture styles. In the approach, XML-based description files are generated for displaying the construction process. What the approach generates are standard architectures that strictly follow the ancient Chinese governmental manual. To demonstrate the efficiency of our approach, architectures in different styles have been generated based on their corresponding rules. The fundamental difference between our approach and previous works is that we apply and implement the module system in digitalization of ancient Chinese architecture.