Modeling complex architectures is quite challenging. We introduce a novel intelligent system, which can generate semi-style or semi-structure Chinese ancient architectures automatically. By using an ontology based approach to analyze the styles of different architectures, geometry primitives (e.g. point, line, triangle, etc.) are converted into semantic architecture components (e.g. window, gate, roof, etc.) as knowledge. The following modeling process can be performed at different semantic levels, and it is appealing to users having domain knowledge. This intelligent architecture modeling system has been successfully applied in the digital heritage project for ancient architectures in southeast China.