3D city modeling is an interesting subject that attracts both computer aided design and computer graphics communities. This paper surveys the recent development of 3D city modeling techniques for either real or virtual city. Some typical approaches and fundamenta1 principles behind them are also analyzed and compared. Finally we introduce a rule-driven procedure modeling approach for large-scale virtual city. Comparing with the existing approaches, the rules adopted by the proposed approach and based on urban planning principles are easy to be understood and customized. Our experiments proved the system is effective and efficient.